bluuebunny/crossref_metadata_2025 huggingface dataset:
Mean-field approximation of the Fermi–Hubbard model expressed in a many-body basis
Authors: Honet Antoine , Henrard Luc , Meunier Vincent
Published: July 2023

The effective independent-particle (mean-field) approximation of the Fermi–Hubbard Hamiltonian is described in a many-body basis to develop a formal comparison with the exact diagonalization of the full Fermi–Hubbard model using small atomic chain as test systems. This allows for the development of an intuitive understanding of the shortcomings of the mean-field approximation and how critical correlation effects are missed in this popular approach. The description in the many-body basis highlights a potential ambiguity related to the definition of the density of states. Specifically, satellite peaks are shown to emerge in the mean-field approximation, in departure from the common belief that they characterize correlation effects. The scheme emphasizes the importance of correlation and how different many-body corrections can improve the mean-field description. The pedagogical treatment is expected to make it possible for researchers to acquire an improved understanding of many-body effects as found in various areas related to the electronic properties of molecules and solids.
Ab initio study of electric field effects on phonon vibrations in tetragonal ZrO2
Authors: Masuda Hiroshi , Tamao Daiki , Yoshida Hidehiro
Published: July 2023

The effects of external electric fields on phonon-associated phenomena, such as phase transformation and diffusion in ZrO2 ceramics, have been reported from recent experiments. This study examined the effects of external direct current (DC) electric fields on the phonon vibration properties in a tetragonal ZrO2 unit cell based on the density-functional perturbation theory. Phonon dispersions and densities of states were analyzed with optimized structures under varying external DC electric fields up to 45 mV/Å. The field sensitivities of phonon characteristics exhibited significant orientation dependence and were attributed to ionic polarization associated with symmetry breaking in dielectric properties. Optical phonons showed considerable field sensitivities particularly near the Brillouin zone boundaries, such as in the M (π/a, π/a, 0) to X (0, π/a, 0) and A (π/a, π/a, π/c) to R (0, π/a, π/c) directions, where doubly degenerate phonon frequencies exhibited splitting behaviors associated with the symmetry breaking between two unique oxygen atoms in the original unit cell. In contrast, transversal acoustic phonons demonstrated a softening trend with increasing field strengths around the Z (0, 0, π/c) point, where imaginary and splitting frequencies were obtained under electric fields of >40 mV/Å, indicating the potential phase transformation from the tetragonal to orthorhombic symmetries under strong external electric fields.
PhysNet meets CHARMM: A framework for routine machine learning/molecular mechanics simulations
Authors: Song Kaisheng , Käser Silvan , Töpfer Kai , Vazquez-Salazar Luis Itza , Meuwly Markus
Published: July 2023

Full-dimensional potential energy surfaces (PESs) based on machine learning (ML) techniques provide a means for accurate and efficient molecular simulations in the gas and condensed phase for various experimental observables ranging from spectroscopy to reaction dynamics. Here, the MLpot extension with PhysNet as the ML-based model for a PES is introduced into the newly developed pyCHARMM application programming interface. To illustrate the conception, validation, refining, and use of a typical workflow, para-chloro-phenol is considered as an example. The main focus is on how to approach a concrete problem from a practical perspective and applications to spectroscopic observables and the free energy for the –OH torsion in solution are discussed in detail. For the computed IR spectra in the fingerprint region, the computations for para-chloro-phenol in water are in good qualitative agreement with experiment carried out in CCl4. Moreover, relative intensities are largely consistent with experimental findings. The barrier for rotation of the –OH group increases from ∼3.5 kcal/mol in the gas phase to ∼4.1 kcal/mol from simulations in water due to favorable H-bonding interactions of the –OH group with surrounding water molecules.
Direct observation of antiferromagnetic domains and field-induced reversal in Pt/Cr2O3/Pt epitaxial trilayers
Authors: Ujimoto Kakeru , Sameshima Hiroki , Toyoki Kentaro , Kotani Yoshinori , Moriyama Takahiro , Nakamura Kohji , Nakatani Ryoichi , Shiratsuchi Yu
Published: July 2023

Antiferromagnet does not show the net magnetization, whereas the finite uncompensated moment can residue at the surface. On the surface of the magnetoelectric antiferromagnet, the finite boundary magnetization can acquire the magnetic response. In this paper, we address the magnetic response of the boundary magnetization in the Pt/magnetoelectric Cr2O3/Pt epitaxial trilayer based on the anomalous Hall effect (AHE) and the soft x-ray magnetic circular dichroism (XMCD). Decreasing the Cr2O3 thickness down to 15 nm, the film acquired the magnetic responsiveness, which manifested as the rectangular hysteresis in the magnetic field dependence of the AHE. The sizable XMCD intensity and the rectangular magnetic field dependence of the XMCD intensity revealed that the magnetic response was attributed to the interfacial Cr moment. The detailed investigation of AHE and XMCD revealed that the domain wall motion dominated the reversal process of the boundary magnetization, which was directly visualized by the scanning XMCD microscope.
Influence of Si(111) substrate off-cut on AlN film crystallinity grown by magnetron sputter epitaxy
Authors: Pingen Katrin , Neuhaus Stefan , Wolff Niklas , Kienle Lorenz , Žukauskaitė Agnė , von Hauff Elizabeth , Hinz Alexander M.
Published: July 2023

The increasing demand for More than Moore devices requires epitaxy technology to keep up with the discovery and deployment of new semiconductors. An emerging technology for cost-effective, device-quality growth is magnetron sputter epitaxy, though detailed studies on the process itself remain scarce. Here, we report an extensive study on the correlation between the substrate off-cut and film quality in AlN-on-Si heteroepitaxy. Controlled reactive pulsed magnetron sputtering is used to grow epitaxial AlN(0001) films on in situ Ar plasma etched off-cut Si(111) substrates with growth rates above 1.5 nm/s. Substrate off-cut angles in the range of 0.02°–0.30° are investigated and precisely determined by high-resolution x-ray diffraction. Structural examination of the AlN films is carried out by transmission electron microscopy and high-resolution x-ray diffraction. The AlN/Si interface is well-defined and two types of AlN domains with epitaxial relationships are observed. The formation of secondary rotation domains deteriorates the crystal quality substantially. Substrates with small off-cuts, ideally no off-cut substrates, appear to be crucial for suppressing the formation of secondary domains and further result in a better overall crystal quality of AlN films. We discuss this effect in relation to the AlN/Si interface, the substrate pre-treatment, and nucleation.
Numerical simulation of fuel supply of multi-tandem fuel tanks in flight vehicle
Authors: Zhang Zijian , Chen Fuzhen , Shi Tengda
Published: July 2023

Multi-tandem fuel tanks have a complex structure, low flow rate between tanks, and, unlike single-fuel tanks, uneven pressure distribution, which makes their fuel supply and pressurization difficult to control. This paper uses a volume-of-fluid model based on the finite-volume method to track the fuel motion in different states of a flight vehicle and obtains the liquid-surface sloshing and the liquid flow in the connecting pipe. The model uses the dynamic meshing technique combined with the pressure at the solid wall to track the motion of the one-way stop valve diaphragm in the connecting pipe, thereby better predicting the fuel transfer in the connecting pipe. The calculation covers the whole process of flight vehicle erection, standby, flight, pumping, and pressurization and provides the distribution of pressure in different fuel tanks and the fuel flow characteristics in the connecting pipe. The calculation results are consistent with the experimental results, which verifies the accuracy of the model. By calculating different working cases, the results show that the different states of the flight vehicle strongly affect the sloshing of the liquid in the fuel tank, the pressure distribution, and the opening and closing of the valves. The maximum mass flow rate through the three valves, pressure at the bottom of the tank, and pressure at the pumping port all increase after the pressurization in the fuel tank. The flow of fuel between different tanks can be increased by changing the structure of the connecting pipe, which affects the pressure at different locations in the tank and at the pumping port.
Energy approach to the description of the dynamics of hydrocarbon spills
Authors: Kistovich A. V. , Chaplina T. O.
Published: July 2023

An energy approach to the problem of theoretical description of axisymmetric and quasi-one-dimensional oil product spills is presented. Within the framework of these models, approximate equations describing the evolution of the size of oil spots over time were derived. Solution of these equations describing the characteristics of spills of both a limited area (for machine oil stains) and unlimited spills of crude oil is obtained. A number of laboratory experiments have been carried out to study the dynamics of spreading of a spot of reference engine oil and crude oil for axisymmetric and quasi-one-dimensional flows. The presented theoretical and experimental results are in good agreement for both spreading regimes.
A conserved RWP-RK transcription factor VSR1 controls gametic differentiation in volvocine algae
Authors: Geng Sa , Hamaji Takashi , Ferris Patrick J. , Gao Minglu , Nishimura Yoshiki , Umen James
Published: July 2023

Volvocine green algae are a model for understanding the evolution of mating types and sexes. They are facultatively sexual, with gametic differentiation occurring in response to nitrogen starvation (-N) in most genera and to sex inducer hormone in
Volvox
. The conserved RWP-RK family transcription factor (TF) MID is encoded by the
minus
mating-type locus or male sex-determining region of heterothallic volvocine species and dominantly determines
minus
or male gametic differentiation. However, the factor(s) responsible for establishing the default
plus
or female differentiation programs have remained elusive. We performed a phylo-transcriptomic screen for autosomal RWP-RK TFs induced during gametogenesis in unicellular isogamous
Chlamydomonas reinhardtii
(Chlamydomonas) and in multicellular oogamous
Volvox carteri
(Volvox) and identified a single conserved ortho-group we named Volvocine Sex Regulator 1 (VSR1). Chlamydomonas
vsr1
mutants of either mating type failed to mate and could not induce expression of key mating-type-specific genes. Similarly, Volvox
vsr1
mutants in either sex could initiate sexual embryogenesis, but the presumptive eggs or androgonidia (sperm packet precursors) were infertile and unable to express key sex-specific genes. Yeast two-hybrid assays identified a conserved domain in VSR1 capable of self-interaction or interaction with the conserved N terminal domain of MID. In vivo coimmunoprecipitation experiments demonstrated association of VSR1 and MID in both Chlamydomonas and Volvox. These data support a new model for volvocine sexual differentiation where VSR1 homodimers activate expression of
plus
/female gamete-specific-genes, but when MID is present, MID-VSR1 heterodimers are preferentially formed and activate
minus
/male gamete-specific-genes.
Strategies for the Biological Control of
Parthenium hysterophorus
L. in Eastern Pakistan
Authors: Rehman Abdul , Kalaugher Liz
Published: July 2023

The arrival of the invasive agricultural weed parthenium,
Parthenium hysterophorus
, in Pakistan was first noted in the Gujrat district of the Punjab Province in 1980. The plant has now spread further in the Punjab Province as well as into Khyber Pakhtunkhwa (KP), the Islamabad Capital Territory (ICT) and Azad Jammu and Kashmir. The heartlands of parthenium infestation are in the central and northern districts of Punjab, the ICT and KP, and the weed is moving into the southern parts of Punjab and north-eastern KP. Given parthenium’s highly invasive nature, it is likely that it has already spread into the southern parts of Punjab, especially as the area is home to extensive irrigated farming, and it is possible that the plant has even reached Sind and Baluchistan provinces in the south and south-west of Pakistan. To date, two biological control agents for parthenium have reached Pakistan without being introduced deliberately, most likely arriving from India or Nepal:
Zygogramma bicolorata
– the Mexican or parthenium leaf beetle – and
Puccinia abrupta partheniicola
, or winter rust.

This case study assesses the effectiveness of these existing biological control agents in Pakistan, the potential of redistribution projects to increase their impact and whether artificially inducing
Z. bicolorata
to emerge from diapause early could further stem parthenium growth in spring. The second part of the case describes the importation of the stem-boring weevil
Listronotus setosipennis
into a quarantine facility for host range testing. The plan is to boost Pakistan’s biological control programme by releasing the weevil in areas where parthenium occurs. Finally, the case also recommends additional biological control agents and strategies for the future.

Adapted from:

The biological control of Parthenium hysterophorus L. in Pakistan: Status quo and future prospects'. Management of Biological Invasions (2021), Volume 12, Issue 3: pages 509-526. This is an open access article distributed under terms of the
Creative Commons Attribution License (Attribution 4.0 International - CC BY 4.0).

Information

© CAB International 2023
Wear properties of Fe-16Mn-10Al-5Ni-0.86C lightweight steel manufactured by laser powder bed fusion
Authors: Kang Tae-Hoon , Kale Amol B. , Kim Han-Soo , Lee Kee-Ahn
Published: July 2023

Microstructural characteristics and wear properties of Fe-16Mn-10Al-5Ni-0.86C lightweight steel (LWS) manufactured by laser powder bed fusion (LPBF) process were investigated and compared with conventional LWS. Both LWS alloys constituted an austenite matrix and B2-IMC. The LPBF LWS sample showed polygonal-typed B2-IMC, whereas conventional LWS had rod-typed B2-IMC. The ball-on-disk method was used to perform a wear test at 25°C under three different load conditions of 20N, 3N and 40N. The wear results indicated that the LPBF LWS sample exhibited a similar amount of wear loss under the 20N and 30N load conditions, but it showed better wear resistance under the 40N compared to conventional LWS. After the wear test, the abrasive wear behaviour was confirmed as the main wear mechanism in both LWSs. The formation of oxide layers and debris was analysed through observation of the cross-sectional area of the worn surface.
Stable reconstruction of simple Riemannian manifolds from unknown interior sources
Authors: de Hoop Maarten V , Ilmavirta Joonas , Lassas Matti , Saksala Teemu
Published: July 2023

Consider the geometric inverse problem: there is a set of delta-sources in spacetime that emit waves travelling at unit speed. If we know all the arrival times at the boundary cylinder of the spacetime, can we reconstruct the space, a Riemannian manifold with boundary? With a finite set of sources we can only hope to get an approximate reconstruction, and we indeed provide a discrete metric approximation to the manifold with explicit data-driven error bounds when the manifold is simple. This is the geometrization of a seismological inverse problem where we measure the arrival times on the surface of waves from an unknown number of unknown interior microseismic events at unknown times. The closeness of two metric spaces with a marked boundary is measured by a labeled Gromov–Hausdorff distance. If measurements are done for infinite time and spatially dense sources, our construction produces the true Riemannian manifold and the finite-time approximations converge to it in the metric sense
Scientific consensus views are useful, but dangerous, without a code of ethics
Authors: Murakami Michio , Yagihashi Mao , Sada Ryuichi Minoda
Published: July 2023

Using the Fukushima accident experience, this letter discusses recent efforts on measuring scientific consensus views—that is, quantifying the agreement among scientists. In the field of radiological protection, the efforts to measure scientific consensus views deserve attention, because hoaxes have been spreading even after the Fukushima nuclear accident. We discussed two points. First, the visualization of the diversity of scientific opinions shatters the diversity illusion caused by the mass media’s irresponsible dissemination of pro and con arguments. Second, the use of scientific consensus views without an ethical code is dangerous. Measuring scientific consensus views should be accompanied with the development of ethical guidelines on using it.
Radiological study of a wastewater treatment plant associated with radioiodine therapy at a hospital in West Java, Indonesia
Authors: Puspita Tita Dewi , Moersidik Setyo Sarwanto , Pratama Mochamad Adhiraga
Published: July 2023

Nuclear medicine (NM) services in Indonesia have rapidly developed due to the increasing number of patients, and this growth has been supported by standardized regulations in the field, including the management of solid waste generated. However, multiple reports indicate that licensing control does not regulate liquid waste disposal from patient excretions to protect personnel and the community from radiopharmaceutical exposure. One of the radiopharmaceuticals commonly used in NM and having the longest half-life among the radiopharmaceuticals used in NM is iodine 131(I-131). Thus, this study used a high-purity germanium detector to measure iodine-131 (I-131) activity in liquid waste from decay tanks, temporary collection channels, the hospital’s wastewater treatment plant (WWTP) outlet, and six points around the NM service and liquid waste treatment unit. Concentration measurements in three decay tanks were carried out sequentially every 12 h for 3 d, corresponding to the therapy period. The results showed that the I-131 activity levels in the decay tanks and temporary collection channels, before being mixed with liquid waste from other units, were 95.9 × 106 ± 4.4 × 106 Bq m−3. At the point where the liquid waste from other units was mixed, the activity level decreased significantly to 472 680 ± 22 160 Bq m−3, which was below the clearance level of 107 Bq m−3. However, the recorded concentration exceeded the standard for environmental radioactivity at the hospital’s WWTP outlet, namely 37 670 ± 2040 Bq m−3. The measurement results for I-131 in the air in the open space for two nuclear buildings was above the standard at 1.3 ± 0.27 Bq m−3. According to the RESRAD simulation, based on the initial dose taken from the liquid waste treatment outlet point, the accumulation of doses and the risk of cancer among workers and the community decreased within 3 months after the maximum exposure.
Metal-organic framework derived CdSe wrapped with rGO for enhanced lithium storage performance
Authors: Wang Fengqin , Ren Qian , Sun Zhenyu , Dong Caifu , Wang Xiaoqing , Wang Yihui
Published: July 2023

Considering the advantages of MOF-based, CdSe-based, and rGO-based materials, CdSe nanoparticles encapsulated with rGO (CdSe@rGO) were synthesized by a metal-organic framework derived method. CdSe nanoparticles encapsulated with rGO can effectively tolerate volume expansion and improve electrical conductivity, leading to excellent cycling stability (396 mAh g−1 at 0.3 A g−1 after 200 cycles, 311 mAh g−1 at 0.5 A g−1 after 500 cycles), and rate performance (562 mAh g−1 at 0.1 A g−1 and 122.2 mAh g−1 at 4 A g−1) for lithium-ion storage. This strategy for preparing metal selenides protected by carbon layers can be extended to the design of other high-performance materials.
Numerical modelling of HTS tapes under arbitrary external field and transport current via integral method: review and application to electrical machines
*
Authors: Chow Calvin C T , Grilli Francesco , Chau K T
Published: July 2023

Superconductors in practical use can be subjected to spatially non-uniform and time-varying external magnetic field as well as carrying a transport current, for example, in an electrical machine. This paper verifies that the integral method can be used in situations in which the external field is spatially non-uniform, by providing both theoretical reasoning and simulation results. Variations in the integral method are reviewed, such as how to impose transport current. Further, the integral method is applied to calculate ac loss in superconducting tapes in an air-cored electrical machine in a two-stage process: the external field is calculated in a COMSOL model without superconducting tapes, and exported into the integral method model that consists of the tapes only. The time taken by the integral method is a small fraction of the time taken by the full machine model in COMSOL, which uses the T-A formulation. There are good agreements between the full COMSOL model and two-stage method incorporating the integral method.
Broadband sub-diffraction focusing of oblique radially polarized wave by a high-numerical-aperture metalens
Authors: Wu Zhixiang , Zou Yiyang , Li Xinyu , Deng Hu , Xiong Liang , Liu Quancheng , Shang Liping
Published: July 2023

Lenses with sub-diffraction focusing are extensively used in advanced optical imaging and microscope. Due to the longitudinal electric component, the radially polarized beam could offer sub-diffraction focusing by high-numerical-aperture (NA) lenses. However, slightly oblique incidence light could pose serious off-axis aberrations for high-NA metalens. ​Here, we demonstrate that a high NA (0.97) metalens design approach can simultaneously provide sub-diffraction focusing for oblique incidence and broadband operation. Simulation results demonstrate that the metalens with an aperture stop, R
stop, of 7 μm have the operating angle range of [–15°, +15°] for sub-wavelength focusing. For the case of R
stop = 9 μm, sub-diffraction focusing is realized in the oblique angle range at ±6°. Significantly, the metalens is able to realize a sub-diffraction focusing over the wavelength range 600–750 nm. These types of metalens have the important advantages of sub-diffraction focusing and broadband operation. They are also ultra-thin and easy to integrate, allowing such metalens could be used in miniaturized and integrated optical systems.
Searching for dark matter subhalos in the Fermi-LAT catalog with Bayesian neural networks
Authors: Butter Anja , Krämer Michael , Manconi Silvia , Nippel Kathrin
Published: July 2023

About a third of the γ-ray sources detected by the Fermi Large Area Telescope (Fermi-LAT) remain unidentified, and some of these could be exotic objects such as dark matter subhalos. We present a search for these sources using Bayesian neural network classification methods applied to the latest 4FGL-DR3 Fermi-LAT catalog. We first simulate the γ-ray properties of dark matter subhalos using models from N-body simulations and semi-analytical approaches to the subhalo distribution. We then assess the detectability of this sample in the 4FGL-DR3 catalog using the Fermi-LAT analysis tools. We train our Bayesian neural network to identify candidate dark matter subhalos among the unidentified sources in the 4FGL-DR3 catalog. Our results allow us to derive conservative bounds on the dark matter annihilation cross section by excluding unidentified sources classified as astrophysical-like by our networks. We estimate the number of candidate dark matter subhalos for different dark matter masses and provide a publicly available list for further investigation. Our bounds on the dark matter annihilation cross section are comparable to previous results and become particularly competitive at high dark matter masses.
Deflection and gravitational lensing with finite distance effect in the strong deflection limit in stationary and axisymmetric spacetimes
Authors: Duan Yujie , Lin Siyan , Jia Junji
Published: July 2023

We study the deflection and gravitational lensing (GL) of both timelike and null signals in the equatorial plane of arbitrary stationary and axisymmetric spacetimes in the strong deflection limit. Our approach employs a perturbative method to show that both the deflection angle and the total travel time take quasi-series forms ∑
n=0 [Cn
ln (1-bc/b) + Dn
] (1-bc/b)
n
, with the coefficients Cn
and Dn
incorporating the signal velocity and finite distance effect of the source and detector. This new deflection angle allows us to establish an accurate GL equation from which the apparent angles of the relativistic images and their time delays are found. These results are applied to the Kerr and the rotating Kalb-Ramond (KR) spacetimes to investigate the effect of the spacetime spin in both spacetimes, and the effective charge parameter and a transition parameter in the rotating KR spacetime on various observables. Moreover, using our approach, the effect of the signal velocity and the source angular position on these variables is also studied.
Friction Coefficient Characteristics of Typical Subway Brake Shoes and Brake Pads in Service
Authors: Guo Ziheng , Zuo Jianyong , Ding Jingxian , Wang Xueping
Published: July 2023

Brake pads and brake shoes are the main components of the friction pair of the subway air brake. At present, the average coefficient of friction is usually used as a criterion for evaluating the braking effect of pads and shoes. In this paper, by analyzing the braking process of the subway, it is inferred that the average friction coefficient has a poor evaluation effect under the low-speed common braking conditions, and a new alternative evaluation index, the equivalent average friction coefficient at low speed, is proposed. The conjecture is verified by the test bench test, and the feasibility of the low-speed equivalent average friction coefficient as an evaluation index under low-speed conditions is proved.
Decentralized Observer-Based Regulations of Multi-Machine Power Systems with Time-Varying Interconnections
Authors: Mao Zheng-Ji , Tseng Yen-Ming , Hu Dan-Hong
Published: July 2023

A decentralized observer-based approach for the regulations of multi-machine power systems with time-varying interconnections is proposed. By using the optimal control method to the observer and nominal equation of each power machine, the optimal solutions are modified to adapt these nonlinear interactions among the power machines. The proposed approach is a truly decentralized output feedback scheme and can guarantee the global system a prescribed chosen degree of stability. Computer simulations of a 3-machine power system are conducted. From these results, we find the observer states follow the real states rapidly and all the states converge to zero exponentially.
Advances in the Analysis of Storage Failure of Solid Rocket Motor
Authors: Qiao Dong , Kong Xiangtong , Meng Shenghao , Feng Shuaixing
Published: July 2023

Solid rocket motor(SRM) in the whole life cycle, to withstand temperature, gravity, vibration, ignition shock, axial overload and other loads, directly affect the life of the engine. Based on the failure mode, failure mechanism and failure criteria of SRM, this paper elaborates and explains the relevant test and numerical simulation methods that affect the storage life of SRM and the method of life analysis, and finds that under the action of individual or compound load, the SRM column will produce a slight lysing damage. These defects will cause great interference to the storage life of SRM, and in the storage process, the SRM will have a creep effect through long-term gravity, which will not only cause the damage to expand the inside of the drug column, but also lead to changes in the shape of the drug, seriously affecting the combustion performance and mechanical performance of the engine. The safety and reliability of solid rocket motors are greatly reduced. The conclusion of this paper is of great significance to the study of storage failure analysis of SRM.
Ptychographical iterative engine based on pixel binning for improving the computational efficiency
Authors: Pei Zihao , Hu Youyou , Yang Zhongming , Dou Jiantai
Published: July 2023

Ptychographical iterative engine (PIE) is an attractive modality of phase retrieval that can provide the quantitative phase of the sample and extend the field of view. For a large sample, a great deal of images with a large dataset are recorded, which will result in high requirements for the computing power and increase the calculation burden. Here, we propose a pixel binning strategy to improve the computational efficiency and reduce the calculation time of PIE. In this method, the recorded image chosen as the amplitude constraint in reconstruction algorithm is compressed by merging the amplitude values of the adjacent positions into one value by the linear superposition, and the compressed pattern is set as a new amplitude constraint to reconstruct the compressed object and probe with fewer pixel number and larger grid size compared to the uncompressed results. Then, the compressed values are extended by the interpolation method. The improvement in the computational efficiency at the point lies in the fact that it takes less time to do the free-space diffraction propagation calculation for images with fewer pixel number. Experiments demonstrate that the proposed method behaves good performance with high computational efficiency. The proposed approach would be helpful for large-scale imaging with high computational efficiency.
Enhancing plasticity of ‘self-sharpening’ tungsten high-entropy alloy via tailoring μ-precipitation
Authors: Li Tong , Chen Jinxi , Chen Feng , Chen Yan , Dai Lanhong
Published: July 2023

In our recently published work (Acta Materialia 186 (2020) 257–266), we have designed a new equimolar tungsten high-entropy alloy with excellent penetration ability to satisfy the highly desirable of ‘self-sharping’ in wide range of engineering application. This alloy has outstanding dynamic compressive properties and superior penetration performance than that of 93 W alloys. In this work, the tension properties of the tungsten high-entropy alloy were significantly improved by μ phase precipitation design strategy to tailor the morphology and distribution of μ phase. Through controlling the phase transformation process, the μ phase changes from liquid-solid phase transformation to solid-solid precipitation phase transformation. This can effectively impede the brittleness caused by the μ phase segregation at the grain boundary and phase boundary. Moreover, the Orowan effect caused by nano-sized μ-phase particles improves the tensile strength effectively (enhancing ∼150%) and ensure the ductility. This material design strategy significantly improves the tension ductility of the alloy and provides a new paradigm to solve the similar problem of material brittleness.
Predictive quality assurance for linear accelerator target failure using statistical process control
Authors: Li Jingdong , Wang Dongxu , Chan Maria
Published: July 2023

The performance of a linear accelerator (Linac) depends on the integrity of its x-ray target. The sudden failure of its target not only breaks down the Linac but also could contribute significant disruptions to patient care. This work is to develop a predicative quality assurance (QA) method using Statistical Process Control (SPC) and AutoRegressive Integrated Moving Average (ARIMA) modeling to identify the risk of target failure before it occurs. In the past years, we observed two incidents of target failure among our Linacs. Retrospectively, we collected past daily QA data (from both open fields and enhanced dynamic wedge (EDW) measurements) and analyzed its historical trend using methods of SPC and ARIMA. SPC is a technique that monitors process performance based on statistical analysis. ARIMA is a time-series forecasting algorithm that can be used to estimate future values based on its past pattern. Both have been evaluated for predictive QA in radiotherapy. Application of SPC on open beam QA data would not yield an early warning signal to the pending target failures. However, when the same SPC methodology applies to EDW measurements, the control limits were breached a couple of weeks before the target failed. EDW mechanism introduces nonuniform magnification factors over its wedge-directed beam profiles and is responsible for the sensitivity of its profile to changing beam properties induced by a degrading target. Further extension of the warning period may be possible by using ARIMA modeling. Predicative QA for EDW daily data using SPC and ARIMA methods may provide an early QA warning to incoming Linac target failure.
Induced luminescence in water and PMMA - spectral analysis for irradiations with proton beams within the clinical energy range
Authors: Burg Jan Michael , Flatten Veronika , Wulff Joerg , Timmermann Beate , Vorwerk Hilke , Zink Klemens
Published: July 2023

It was recently discovered that water and PMMA emit a weak luminescence signal when irradiated with protons within the clinically used energy range. This could offer a fast approach for range measurements in water. However, a complete explanation or investigation on the origin of the signal has not been published. In this work, a setup for the high-resolution spectral measurement of the weak luminescence signal in water and PMMA was designed. The measurement environment in the vicinity of a proton accelerator represented a major challenge for the sensitive optical measurements due to the presence of ionizing scattered radiation. A high-sensitive spectrometer in combination with a custom-made fiber was used to build a foundation for further analysis of the luminescence signal by providing accurate spectral information. For water, a broad distribution in the range from 240 to 900 nm with a maximum at 480 nm was obtained. A comparison of the spectra with previously published work indicates that the signal originates from excited states produced during the radiolysis of water. In comparison, differences between the water and the PMMA spectrum were observed. When examining the signal in PMMA, spectral differences were found compared to the measurements in water. The signal in PMMA was approximately 10 times stronger, had a narrower distribution and was shifted to lower wavelengths. Nevertheless, for the investigated proton energies, no spectral energy dependence was detected. In addition to the results for water and PMMA, a further luminescence signal was measured when the silica fiber used was directly irradiated with primary protons. All spectra, obtained in this work, describe the signal of proton-induced luminescence in water and PMMA with a high resolution of 3.4 nm and thus form a basis for further research, which could be a powerful tool in proton range verification.
Magic state distillation and cost analysis in fault-tolerant universal quantum computation
Authors: Liu Yiting , Ma Zhi , Luo Lan , Du Chao , Fei Yangyang , Wang Hong , Duan Qianheng , Yang Jing
Published: July 2023

Magic states have been widely studied in recent years as resource states that help quantum computers achieve fault-tolerant universal quantum computing. The fault-tolerant quantum computing requires fault-tolerant implementation of a set of universal logical gates. Stabilizer code, as a commonly used error correcting code with good properties, can apply the Clifford gates transversally which is fault tolerant. But only Clifford gates cannot realize universal computation. Magic states are introduced to construct non-Clifford gates that combine with Clifford operations to achieve universal quantum computing. Since the preparation of quantum states is inevitably accompanied by noise, preparing the magic state with high fidelity and low overhead is the crucial problem to realizing universal quantum computation. In this paper, we survey the related literature in the past 20 years and introduce the common types of magic states, the protocols to obtain high-fidelity magic states, and overhead analysis for these protocols. Finally, we discuss the future directions of this field.
Quantum optimisation for continuous multivariable functions by a structured search
Authors: Matwiejew Edric , Pye Jason , Wang Jingbo B
Published: July 2023

Solving optimisation problems is a promising near-term application of quantum computers. Quantum variational algorithms (QVAs) leverage quantum superposition and entanglement to optimise over exponentially large solution spaces using an alternating sequence of classically tunable unitaries. However, prior work has primarily addressed discrete optimisation problems. In addition, these algorithms have been designed generally under the assumption of an unstructured solution space, which constrains their speedup to the theoretical limits for the unstructured Grover’s quantum search algorithm. In this paper, we show that QVAs can efficiently optimise continuous multivariable functions by exploiting general structural properties of a discretised continuous solution space with a convergence that exceeds the limits of an unstructured quantum search. We present the quantum multivariable optimisation algorithm and demonstrate its advantage over pre-existing methods, particularly when optimising high-dimensional and oscillatory functions.
Adaptive active Brownian particles searching for targets of unknown positions
Authors: Kaur Harpreet , Franosch Thomas , Caraglio Michele
Published: July 2023

Developing behavioral policies designed to efficiently solve target-search problems is a crucial issue both in nature and in the nanotechnology of the 21st century. Here, we characterize the target-search strategies of simple microswimmers in a homogeneous environment containing sparse targets of unknown positions. The microswimmers are capable of controlling their dynamics by switching between Brownian motion and an active Brownian particle and by selecting the time duration of each of the two phases. The specific conduct of a single microswimmer depends on an internal decision-making process determined by a simple neural network associated with the agent itself. Starting from a population of individuals with random behavior, we exploit the genetic algorithm NeuroEvolution of augmenting topologies to show how an evolutionary pressure based on the target-search performances of single individuals helps to find the optimal duration of the two different phases. Our findings reveal that the optimal policy strongly depends on the magnitude of the particle’s self-propulsion during the active phase and that a broad spectrum of network topology solutions exists, differing in the number of connections and hidden nodes.
A new algorithm for 𝑝-adic continued fractions
Authors: Murru Nadir , Romeo Giuliano
Published: July 2023

Continued fractions in the field of

p
p

-adic numbers have been recently studied by several authors. It is known that the real continued fraction of a positive quadratic irrational is eventually periodic (Lagrange’s Theorem). It is still not known if a

p
p

-adic continued fraction algorithm exists that shares a similar property. In this paper we modify and improve one of Browkin’s algorithms. This algorithm is considered one of the best at the present time. Our new algorithm shows better properties of periodicity. We show for the square root of integers that if our algorithm produces a periodic expansion, then this periodic expansion will have pre-period one. It appears experimentally that our algorithm produces more periodic continued fractions for quadratic irrationals than Browkin’s algorithm. Hence, it is closer to an algorithm to which an analogue of Lagrange’s Theorem would apply.
An approach to quantify ortho-phthalaldehyde contamination on work surfaces
Authors: Rogers Caitlyn A , Gaskin Sharyn E , Thredgold Leigh D , Pukala Tara L
Published: July 2023

Ortho-phthalaldehyde (OPA) is used as a high-level disinfectant for reusable medical devices in healthcare settings. The ACGIH recently adopted a Threshold Limit Value–Surface Limit (TLV–SL; 25 µg/100 cm2) for OPA surface contamination to prevent induction of dermal and respiratory sensitization following dermal exposure. However, there is no current validated method to measure OPA surface contamination. This study aimed to develop a standardized approach for sample collection and quantitative determination of OPA from work surfaces for use in risk assessment practices. The reported method utilises readily available commercial wipes to collect surface samples coupled with direct detection of OPA via liquid chromatography time of flight mass spectrometry (LC–ToF–MS). This approach avoided complex derivatization steps commonly required for the analysis of aldehydes. Method evaluation was conducted in accordance with the Occupational Safety and Health Administration (OSHA) surface sampling guidelines. Overall recoveries of 25 µg/100 cm2 of OPA from stainless steel and glass surfaces were 70% and 72%, respectively. The reported LOD for this method was 1.1 µg/sample and the LOQ was 3.7 µg/sample. OPA remained stable on the sampling medium for up to 10 days, when stored at 4 °C. The method was demonstrated in a workplace surface assessment at a local hospital sterilising unit, successfully detecting OPA on work surfaces. This method is intended to supplement airborne exposure assessment and provide a quantitative assessment tool for potential dermal exposure. When used in conjunction with a thorough occupational hygiene program that includes hazard communication, engineering controls, and personal protective equipment, skin exposure and consequent sensitization risks in the workplace can be minimized.
Systolic Blood Pressure Less Than 120 mmHg is a Safe and Effective Method to Minimize Bleeding After Facelift Surgery: A Review of 502 Consecutive Cases
Authors: Bassiri-Tehrani Brian , Abi-Rafeh Jad , Baker Nusaiba F , Kerendi Alex N , Nahai Foad
Published: July 2023

Background

Hematoma is the most common complication after facelift surgery. Hypertension is the major risk factor for hematoma following facelift. Measures taken to reduce systolic blood pressure perioperatively significantly reduce the risk of hematoma. There is evidence that treating systolic blood pressure of 140 mmHg or above reduces hematoma; there were no studies to date in which systolic blood pressures below 120 mmHg had been evaluated.

Objectives

To assess the safety and efficacy of maintaining systolic blood pressures of 120 mmHg or less postoperatively to reduce hematoma after facelift.

Methods

A retrospective chart review of a single surgeon’s series of facelift procedures from January 2004 to July 2018 was undertaken. Implementation of a more stringent perioperative blood pressure protocol (maintaining a systolic blood pressure of less than 120 mmHg postoperatively) was initiated in January of 2013, dividing patients into 2 groups.

Results

A total of 502 consecutive patients who underwent a facelift by F.N. were included in the study. A total of 319 patients underwent a facelift before 2013, and a total of 183 patients underwent a facelift in 2013 or later. Overall, a total of 13 hematomas occurred during the entire 15-year study period (2.59%), of which 12 occurred before the implementation of a strict blood pressure regimen (3.76%), and only 1 occurred after the new protocol (0.5%). There were no adverse events related to the lower blood pressure.

Conclusions

Treating systolic blood pressure greater than 120 mmHg postoperatively is a safe and effective method for reducing the risk of hematoma after facelift.
Border Control and the Degradation of Labour
Authors: Bosworth Mary
Published: July 2023

This article uses testimonies from private sector staff about their experiences of working in sites of short-term immigration detention and in facilitating deportation, to explore the material conditions of this form of custodial labour. Until now, most criminological accounts of criminal justice or border staff have paid little attention to them as workers. As a result, the connections between sites and practices of custody and capital have been obscured. Drawing on a range of scholarship about the labour market and the nature of work, the piece concludes by advocating for new alliances to challenge the precarity and poverty that both lead people into these jobs and justifies them and the exclusionary and divisive politics they engender.
Prognostic models for surgical-site infection in gastrointestinal surgery: systematic review
Authors: McLean Kenneth A , Goel Tanvi , Lawday Samuel , Riad Aya , Simoes Joana , Knight Stephen R , Ghosh Dhruva , Glasbey James C , Bhangu Aneel , Harrison Ewen M ,   NIHR Global Health Research Unit on Global Surgery
Published: July 2023

Background

Identification of patients at high risk of surgical-site infection may allow clinicians to target interventions and monitoring to minimize associated morbidity. The aim of this systematic review was to identify and evaluate prognostic tools for the prediction of surgical-site infection in gastrointestinal surgery.

Methods

This systematic review sought to identify original studies describing the development and validation of prognostic models for 30-day SSI after gastrointestinal surgery (PROSPERO: CRD42022311019). MEDLINE, Embase, Global Health, and IEEE Xplore were searched from 1 January 2000 to 24 February 2022. Studies were excluded if prognostic models included postoperative parameters or were procedure specific. A narrative synthesis was performed, with sample-size sufficiency, discriminative ability (area under the receiver operating characteristic curve), and prognostic accuracy compared.

Results

Of 2249 records reviewed, 23 eligible prognostic models were identified. A total of 13 (57 per cent) reported no internal validation and only 4 (17 per cent) had undergone external validation. Most identified operative contamination (57 per cent, 13 of 23) and duration (52 per cent, 12 of 23) as important predictors; however, there remained substantial heterogeneity in other predictors identified (range 2–28). All models demonstrated a high risk of bias due to the analytic approach, with overall low applicability to an undifferentiated gastrointestinal surgical population. Model discrimination was reported in most studies (83 per cent, 19 of 23); however, calibration (22 per cent, 5 of 23) and prognostic accuracy (17 per cent, 4 of 23) were infrequently assessed. Of externally validated models (of which there were four), none displayed ‘good’ discrimination (area under the receiver operating characteristic curve greater than or equal to 0.7).

Conclusion

The risk of surgical-site infection after gastrointestinal surgery is insufficiently described by existing risk-prediction tools, which are not suitable for routine use. Novel risk-stratification tools are required to target perioperative interventions and mitigate modifiable risk factors.