bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of carbide ceramics and coke on the properties of dispersion strengthened aluminium‐silicon7‐magnesium hybrid composites
Authors: Dhas D. S. E. J. , Raja R. , Jannet S. , Wins K. L. D. , Thomas J. M. , Kandavalli S. R.
Published: February 2023

In this study, aluminium‐silicon7‐magnesium alloy was reinforced with carbide ceramics (silicon carbide and boron carbide) and coke microparticles. The composite samples (S1, S2, and S3) with 4 %, 8 %, and 12 % by weight of silicon carbide and boron carbide microparticles and 8 % by weight of coke micro particles respectively, were prepared through the ultrasonic assisted melt‐stir casting route. It was observed from the literature that only a few research works reported the cumulative effect of adding these micro‐particulate reinforcements within aluminium‐silicon7‐magnesium alloy. The microstructural evaluation revealed uniform dispersion of particulate reinforcements. Area energy dispersive x‐ray spectroscopy scan results proved the presence of the reinforcement particles as heterogeneous phases at distinct zones. The samples undergone tensile tests failed under the brittle fracture mode. The ultimate tensile strength of the composites improved by about 27.4 %, the % elongation improved by about 6.8 %, and Vickers microhardness dropped 1.9 % to the maximum. Dimples were observed in the fracture morphology analysis and it was mainly due to the mixed ductility of the sample S2. An abrasive wear mechanism was observed in the worn‐out sample S2. The wear rate decreased significantly with an increase in weight fraction of the reinforcements.
Robust design in material machining on basis of probability multi‐objective optimization
Authors: Zheng M. , Teng H. , Wang Y.
Published: February 2023

This paper regulates a rational approach of robust design in material machining process on basis of the probability method for multi‐objective optimization. As an expansion, it takes the arithmetic mean value of the performance index of the alternative and its deviation as twin independent responses to make contributions of two parts of the partial favorable probability individually; the arithmetic mean value of the performance index represents the performance index according to its function and preference in the assessment, and the deviation exhibits an index with the characteristic of the smaller the better in general. Furthermore, the product of the above twin parts of partial favorable probability forms the actual favorable probability of the performance index of each alternative in the treatment, which is the unique indicator of the performance index of the alternative in the robust optimum. Moreover, examples are given to illustrate the application of the approach.
Timoshenko beams with variable‐exponent nonlinearity
Authors: Mustafa Muhammad I.
Published: February 2023

In this paper, we consider the following Timoshenko system

with a nonlinear feedback having a variable exponent
and a time‐dependent coefficient
. We establish, for the first time as per our knowledge, explicit energy decay rates for this system depending on both
and
. Our result generalizes and improves earlier related results in the literature.
Spatially tunable and self‐healing plasmonic Talbot imaging by using periodic metal nanopore arrays
Authors: Bo Ruirui , Zhang Shuanggen , Pi Shuang , Wang Shumin
Published: February 2023

Plasmonic Talbot imaging exhibits unique advantages over conventional Talbot imaging owing to the potential possibility of the miniaturization and integration of optoelectronic devices. However, the fixed structure parameters limit imaging manipulation, and the defects of masks also affect imaging integrity. Here, we propose a plasmonic Talbot imaging scheme based on the periodic metal nanopore arrays to achieve spatially tunable and self‐healing performance evaluated by the FDTD method. The results reveal that the transverse field distribution at the Talbot planes can be offset in the 500 nm range with the incident light angle changed from 0° to 25°, exhibiting a tunability of the spatial position. Meanwhile, the randomly missing and misaligned defects of such periodic metal nanopore arrays can be effectively restored by the presence of low density or defects located at the center. The feasibility of spatial tunability and self‐healing may provide an opportunity for optical imaging, nanolithography, and phase manipulation.
Meta‐modeling of fractional constitutive relationships for rocks based on physics‐induced machine learning
Authors: Qu Peng‐Fei , Zhang Li‐Mao , Zhu Qi‐Zhi
Published: February 2023

A fractional constitutive meta‐model for the mechanical behavior of rocks is proposed to bypass complex integration algorithms and consider the uncertainty of model/material parameters. First, a physics‐induced database is constructed with the aid of a fractional constitutive model and two developed input–output strategies. Then three machine algorithms (i.e., random forests, extreme gradient boosting, and multilayer perceptron) together with two input–output strategies are employed to formulate six different meta‐models. The grid‐search and five‐fold cross‐validation methods are utilized to optimize key hyperparameters of meta‐models. Through the comparisons of evaluation metrics and prediction results, the multilayer perceptron algorithm with strategy II becomes an optimal combination to construct the meta‐model. The results of the feature's importance and sensitivity analyses indicate that the parameters' influences in this data‐driven paradigm are in line with physical reality. The effectiveness of the proposed meta‐model is validated by comparing the predicted results with experimental observations from the literature. Additionally, the uncertainty analyses from the meta‐model and material/model parameters can be conducted based on a linear regression model and the Monte Carlo simulation. The study results show that the presented meta‐model based on physics‐guided synthetic data has the potential to replace the general fractional constitutive model.
Wafer‐scale single‐crystalline MoSe2 and WSe2 monolayers grown by molecular‐beam epitaxy at low‐temperature — the role of island‐substrate interaction and surface steps
Authors: Xia Yipu , Ding Degong , Xiao Ke , Zhang Junqiu , Xu Shaogang , He Daliang , Yue Xingyu , Rao Qing , Wang Xiong , Ding Sujuan , Gao Guoyun , Xue Hongxia , Wang Yueyang , Yuan Mengfei , Ho Wingkin , Ki Dong‐Keun , Xu Hu , Cui Xiaodong , Jin Chuanhong , Xie Maohai
Published: February 2023

Ultrathin two‐dimensional transition‐metal dichalcogenides (TMDs) have been pursued extensively in recent years for interesting physics and application potentials. For the latter, it is essential to synthesize crystalline TMD monolayers at wafer‐scale. Here, we report growth of single‐crystalline MSe2 (M = Mo, W) monolayers at wafer‐scale by molecular‐beam epitaxy at low temperatures (200–400°C) on nominally flat Au(1 1 1) substrates. The epifilms have low intrinsic defect densities of low 1012 cm−2. The grown films have then been exfoliated and transferred onto SiO2/Si by a wet chemical process, on which some optical measurements are performed, revealing high spatial uniformity of the samples. We also establish that MSe2 grows on Au via the van der Waals epitaxy mechanism, where a continuous film extends across the whole surface, overhangs atomic‐layer steps on substrate. We identify that the growth of highly crystalline MSe2 is promoted by an enhanced interaction between Au substrate and MSe2 islands rather than by the guidance of surface steps on substrate. The latter only arrests MSe2 lateral growth if they are multilayer high.

Key points

MBE growth of wafer‐scale highly crystalline TMD monolayers at low‐temperature is achieved.

Island‐substrate interaction is found to play a critical role in vdW epitaxy of single‐crystalline TMDs on on‐axis substates.

The TMD monolayers are of high uniformity and low intrinsic defect density.
Directed evolution of angiotensin‐converting enzyme 2 peptidase activity profiles for therapeutic applications
Authors: Heinzelman Pete , Romero Philip A.
Published: February 2023

Angiotensin‐converting enzyme 2 (ACE2) has been investigated for its ability to beneficially modulate the angiotensin receptor (ATR) therapeutic axis to treat multiple human diseases. Its broad substrate scope and diverse physiological roles, however, limit its potential as a therapeutic agent. In this work, we address this limitation by establishing a yeast display‐based liquid chromatography screen that enabled use of directed evolution to discover ACE2 variants that possess both wild‐type or greater Ang‐II hydrolytic activity and improved specificity toward Ang‐II relative to the off‐target peptide substrate Apelin‐13. To obtain these results, we screened ACE2 active site libraries to reveal three substitution‐tolerant positions (M360, T371, and Y510) that can be mutated to enhance ACE2's activity profile and followed up on these hits with focused double mutant libraries to further improve the enzyme. Relative to wild‐type ACE2, our top variant (T371L/Y510Ile) displayed a sevenfold increase in Ang‐II turnover number (kcat), a sixfold diminished catalytic efficiency (kcat/Km) on Apelin‐13, and an overall decreased activity on other ACE2 substrates that were not directly assayed in the directed evolution screen. At physiologically relevant substrate concentrations, T371L/Y510Ile hydrolyzes as much or more Ang‐II than wild‐type ACE2 with concomitant Ang‐II:Apelin‐13 specificity improvements reaching 30‐fold. Our efforts have delivered ATR axis‐acting therapeutic candidates with relevance to both established and unexplored ACE2 therapeutic applications and provide a foundation for further ACE2 engineering efforts.
Time Evolution of Long‐Range Ordering in Fe–Pt Alloys
Authors: Ponomarova Svitlana
Published: February 2023

A method to calculate the atomic long‐range order (LRO) parameter and the time to reach an asymptotic LRO value is proposed and applied to a wide concentration range of Fe–Pt alloys with fcc crystal structure. The equation for the time evolution of the LRO parameter is based on a phenomenological approach with Onsager kinetic coefficients as diffusion coefficients for an alloy that undergoes complex combination of phase transformations, that is, atomic and magnetic ordering and martensitic transformation. The microscopic phase‐field kinetic model that was first proposed by Khachaturyan is applied. The energy parameter mixing energy that defines the kinetics of the LRO is considered as a sum of “paramagnetic” (electrochemical + strain‐induced interactions) and Ising‐type magnetic contributions.
Noninteger Valence in Ce‐Based Compounds
Authors: Ponomarova Svitlana , Koval Yurii
Published: February 2023

Herein, a simple thermodynamic approach using the Helmholtz free energy is proposed to estimate the noninteger valence in Ce‐based compounds at the γ→α phase transition. The idea of an electron phase transition within Anderson–Kondo model is used as a microscopic mechanism and applied to Ce–X (X = Y, Al–Sc) within 0–16 at% of X. In the suggested approach, valence of Ce–X compounds depends on volume collapse and the temperatures of start and finish of phase transition as well as external pressure, which can induce γ→α phase transition, and increases with rising the amount of impurity.
COVID‐19: Prevention, Detection, and Treatment by Using Carbon Nanotubes‐Based Materials
Authors: Hatta Mohd Hayrie Mohd , Matmin Juan , Malek Nik Ahmad Nizam Nik , Kamisan Farah Hidayah , Badruzzaman Aishah , Batumalaie Kalaivani , Ling Lee Siew , Abdul Wahab Roswanira
Published: February 2023

The novel severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) was responsible for the outbreak of coronavirus disease (COVID‐19). The respiratory illness has rapidly spread worldwide and has claimed millions of lives. Although most countries have entered the endemic phase, health authorities warned that future variants could be more virulent than the existing ones. Since clinical trials of antiviral drugs for COVID‐19 may last even a year before approval, developing alternative approaches to combat the virus becomes mandatory. Previously, carbon nanotubes (CNTs) have exhibited an impressive track record in controlling numerous viral diseases, including COVID‐19. In this article, we review recent applications of CNTs for the prevention, detection, and treatment of COVID‐19. We highlight the strategies and prospective developments of CNTs in producing personal protection equipment (PPE), vaccines, immune‐triggering, development of biosensors and therapeutic strategies. Finally, the challenges, limitations, and future outlook of CNTs in combating COVID‐19 are also discussed.
Study on the Preparation and Optical Properties of Co‐polycarbonates Based on Binaphthalene and Cardo Structures
Authors: Li Chen , Long Xin , Sun Teng , Wang Qingyin , Wang Gongying
Published: February 2023

Copolymer carbonate was synthesized from diphenyl carbonate (DPC), 9, 9‐bis [3‐phenyl‐4 ‐(2‐hydroxyethoxy) phenyl] fluorene (BPPEF) and 2,2′ ‐bis (2‐hydroxy‐ethoxy)‐1,1′ ‐binaphthalene (BHEBN) by melt transesterification. The composition and random structure of the copolymer were determined by FT‐IR, 1H NMR and 13C NMR analysis. DSC and TGA analysis showed that Cardo structure could significantly increase the glass transition temperature and thermal decomposition temperature. With the addition of BHEBN, the refractive index of copolymer was increased, but the thermal properties of copolymer were decreased. It is found that the contribution of naphthalene structure to the refractive index of the polymer material is higher than that of benzene structure. When the dosage of BHEBN is 42 mol %, the glass transition temperature (Tg) of the copolymer is 141.8 °C, the maximum thermal decomposition temperature is 421.9 °C, the refractive index is 1.6535, the Abbe number is 21, the transmittance is 88.29 %, and the birefringence is negative 0.01×10−3.
Wearable Electronics Based on Stretchable Organic Semiconductors
Authors: Xu Xinzhao , Zhao Yan , Liu Yunqi
Published: February 2023

Wearable electronics are attracting increasing interest due to the emerging Internet of Things (IoT). Compared to their inorganic counterparts, stretchable organic semiconductors (SOSs) are promising candidates for wearable electronics due to their excellent properties, including light weight, stretchability, dissolubility, compatibility with flexible substrates, easy tuning of electrical properties, low cost, and low temperature solution processability for large‐area printing. Considerable efforts have been dedicated to the fabrication of SOS‐based wearable electronics and their potential applications in various areas, including chemical sensors, organic light emitting diodes (OLEDs), organic photodiodes (OPDs), and organic photovoltaics (OPVs), have been demonstrated. In this review, some recent advances of SOS‐based wearable electronics based on the classification by device functionality and potential applications are presented. In addition, a conclusion and potential challenges for further development of SOS‐based wearable electronics are also discussed.
High‐Performing Atomic Electrocatalyst for Chlorine Evolution Reaction
Authors: Ha Miran , Thangavel Pandiarajan , Dang Ngoc Kim , Kim Dong Yeon , Sultan Siraj , Lee Jae Sung , Kim Kwang S.
Published: February 2023

Electrocatalysts facilitating chlorine evolution reaction (ClER) play a vital role in chlor–alkali industries. Owing to a huge amount of chlorine consumed worldwide, inexpensive high‐performing catalysts for Cl2 production are highly demanded. Here, a superb ClER catalyst fabricated through uniform dispersion of Pt single atoms (SAs) in C2N2 moieties of N‐doped graphene (denoted as Pt‐1) is presented, which demonstrates near 100% exclusive ClER selectivity, long‐term durability, extraordinary Cl2 production rate (3500 mmol h−1 gPt−1), and >140 000‐fold increased mass activity over industrial electrodes in acidic medium. Excitingly, at the typical chlor–alkali industries’ operating temperature (80 °C), Pt‐1 supported on carbon paper electrode requires a near thermoneutral ultralow overpotential of 5 mV at 1 mA cm−2 current density to initiate the ClER, consistent with the predicted density functional theory (DFT) calculations. Altogether these results show the promising electrocatalyst of Pt‐1 toward ClER.
Enantioseparation Membranes: Research Status, Challenges, and Trends
Authors: Cheng Qingsong , Ma Qian , Pei Hebing , He Simin , Wang Rui , Guo Ruibin , Liu Nijuan , Mo Zunli
Published: February 2023

The purity of enantiomers plays a critical role in human health and safety. Enantioseparation is an effective way and necessary process to obtain pure chiral compounds. Enantiomer membrane separation is a new chiral resolution technique, which has the potential for industrialization. This paper mainly summarizes the research status of enantioseparation membranes including membrane materials, preparation methods, factors affecting membrane properties, and separation mechanisms. In addition, the key problems and challenges to be solved in the research of enantioseparation membranes are analyzed. Last but not least, the future development trend of the chiral membrane is expected.
Modeling and design of concrete hinges under general loading
Authors: Markić Tomislav , Kaufmann Walter
Published: February 2023

Despite their successful applications in practice for over a century, the design of concrete hinges still entails considerable modeling uncertainty. Their dimensioning still relies on semi‐empirical recommendations originally proposed for admissible stress design, based on limited experimental data and generalized with engineering judgment. This presumably results in overly conservative designs in many cases, particularly when applied with modern design codes based on partial safety factors. This paper addresses these issues by revisiting the analytical modeling for one‐way Freyssinet concrete hinges under general loading based on approaches compatible with current design codes. A cross‐sectional analysis with confined concrete properties is proposed for the behavior under axial forces and bending moments, where the strength of the triaxially compressed concrete in the hinge throat is determined with a discontinuous stress field. The hinge resistance to shear forces is investigated with failure mechanisms inspired by failure modes observed in experiments. Based on the shear strength, a simple approach to estimate the torsional resistance of the throat is proposed. Remarks are also made on the analysis of combined actions. The predictions of the proposed models are validated against a wide range of test data, including a series of recently conducted own experiments. Overall, the proposed models agree better with the available experimental data than the existing approaches, potentially allowing for a more efficient design of new and assessment of existing concrete hinges.
Declines in prey production during the collapse of a tailwater Rainbow Trout population are associated with changing reservoir conditions
Authors: Yard Michael D. , Yackulic Charles B. , Korman Josh , Dodrill Michael J. , Deemer Bridget R.
Published: February 2023

Objective

Understanding how energy moves through food webs and limits productivity at various trophic levels is a central question in aquatic ecology and can provide insight into drivers of fish population dynamics since many fish populations are food limited. In this study, we seek to better understand what factors drove a decline of >85% in the number of Rainbow TroutOncorhynchus mykiss found in the tailwater portion of the Colorado River below Glen Canyon Dam during 2012–2016.

Methods

We estimate the production of dominant prey using data from previously published studies of Rainbow Trout abundance and growth alongside drift and diet samples. We test how prey production correlates to both proximate (e.g., nutrients) and distal (e.g., limnological conditions in the upriver reservoir) drivers.

Result

Results suggest that gross consumption of invertebrate prey by the Rainbow Trout population declined from an annual mean of 423 to 69 kg/d. Daily production rates of dominant prey in aggregate declined from a high of 0.173 to 0.018 g·m−2·d−1. Chironomids accounted for 70% of the decline in prey production. Foraging efficiency by Rainbow Trout (range, 0.99–0.67) was high across the range of prey production rates. After the Rainbow Trout population had declined by ~90%, prey consumption saturated at higher rates of prey production and the gross quantity of daily drift exported from the reach increased from 8.9 to 12.7 kg/d.

Conclusion

Rainbow Trout population dynamics are largely influenced by changes in prey production, which is itself driven by soluble reactive phosphorus (SRP) concentrations in the reservoir. The SRP model predicted that prey production would increase by 32 kg/d (SE, 9) for each 1 μg/L increase in SRP. These concentrations were indirectly influenced by reservoir hydrology and biogeochemistry, linkages that may extend far beyond the confines of this tailwater fishery and into the downstream reaches of the Grand Canyon's Colorado River ecosystem.
Antimicrobial resistance patterns and characterisation of emerging beta‐lactamase‐producing Escherichia coli in camels sampled from Northern Kenya
Authors: Akunda Irene Karegi , Kariuki Daniel W. , Matulis Graham , Mwaura Patrick , Maina Brian , Mohammed Halima , Paul Ayieko , Onyambu Frank G. , ole Kwallah Allan , Martins Dino J. , von Fricken Michael E. , Kamau Joseph M.
Published: February 2023

Background

Animal husbandry practices in different livestock production systems and increased livestock–wildlife interactions are thought to be primary drivers of antimicrobial resistance (AMR) in Arid and Semi‐Arid Lands (ASALs). Despite a tenfold increase in the camel population within the last decade, paired with widespread use of camel products, there is a lack of comprehensive information concerning beta‐lactamase‐producing Escherichia coli (E. coli) within these production systems.

Objectives

Our study sought to establish an AMR profile and to identify and characterise emerging beta‐lactamase‐producing E. coli isolated from faecal samples obtained from camel herds in Northern Kenya.

Methods

The antimicrobial susceptibility profiles of E. coli isolates were established using the disk diffusion method, with beta‐lactamase (bla) gene PCR product sequencing performed for phylogenetic grouping and genetic diversity assessments.

Results

Here we show, among the recovered E. coli isolates (n = 123), the highest level of resistance was observed for cefaclor at 28.5% of isolates, followed by cefotaxime at 16.3% and ampicillin at 9.7%. Moreover, extended‐spectrum beta‐lactamase (ESBL)‐producing E. coli harbouring the blaCTX‐M‐15 or blaCTX‐M‐27 genes were detected in 3.3% of total samples, and are associated with phylogenetic groups B1, B2 and D. Multiple variants of non‐ESBL blaTEM genes were detected, the majority of which were the blaTEM‐1 and blaTEM‐116 genes.

Conclusions

Findings from this study shed light on the increased occurrence of ESBL‐ and non‐ESBL‐encoding gene variants in E. coli isolates with demonstrated multidrug resistant phenotypes. This study highlights the need for an expanded One Health approach to understanding AMR transmission dynamics, drivers of AMR development, and appropriate practices for antimicrobial stewardship in camel production systems within ASALs.
A meta‐analysis of shrub density as a predictor of animal abundance
Authors: Zuliani Mario , Ghazian Nargol , Lortie Christopher J.
Published: February 2023

Facilitative interactions between shrub and animal species influence the structure and composition of communities. The benefits associated with woody shrub species can critically influence local animal populations, in particular. Here, we tested the relative importance of the density of shrub species on the local abundance of animal populations using a meta‐analysis. Full‐text review for shrub density, animal abundance or density and sampling effort, resulted in a total of 113 independent observations that reported both shrub density and animal abundance. A meta‐regression of shrub density on animal density with feeding functional group of the animal species as a moderator was used to test the predictive capacity of this simple vegetation measure on animal populations. Shrub density positively predicted animal abundance in these studies – particularly in deserts and grasslands. Shrub and woody plant density can thus be used as a potential rapid proxy for habitat in predicting local animal abundances. This method can support restoration and conservation of resident animal species in impacted ecosystems structured by woody shrubs globally.
Holographic measurement and quantum teleportation in the SYK thermofield double
Authors: Antonini Stefano , Grado-White Brianna , Jian Shao-Kai , Swingle Brian
Published: February 2023

Abstract

According to holography, entanglement is the building block of spacetime; therefore, drastic changes of entanglement will lead to interesting transitions in the dual spacetime. In this paper, we study the effect of projective measurements on the Sachdev-Ye-Kitaev (SYK) model’s thermofield double state, dual to an eternal black hole in Jackiw-Teitelboim (JT) gravity. We calculate the (Renyi-2) mutual information between the two copies of the SYK model upon projective measurement of a subset of fermions in one copy. We propose a dual JT gravity model that can account for the change of entanglement due to measurement, and observe an entanglement wedge phase transition in the von Neumann entropy. The entanglement wedge for the unmeasured side changes from the region outside the horizon to include the entire time reversal invariant slice of the two-sided geometry as the number of measured Majorana fermions increases. Therefore, after the transition, the bulk information stored in the measured subsystem is not entirely lost upon projection in one copy of the SYK model, but rather teleported to the other copy. We further propose a decoding protocol to elucidate the teleportation interpretation, and connect our analysis to the physics of traversable wormholes.
Hot and dense QCD shear viscosity at leading log
Authors: Danhoni Isabella , Moore Guy D.
Published: February 2023

Abstract

The leading-order weak-coupling shear viscosity of QCD was computed almost 20 years ago, and the extension to next-to-leading order is 4 years old. But these results have never been applied at finite baryon chemical potentialμ, despite the fact that intermediate-energy heavy ion collisions and merging neutron stars may explore the Quark-Gluon Plasma in a regime where baryon chemical potentials are large. Here we extend the leading-log shear viscosity calculation to finiteμ, and we argue that the convergence of the weak-coupling expansion, while questionable for achievable plasmas, should be better atμ > Tthan atμ= 0.
Fractional Hall conductivity and spin-c structure in solvable lattice Hamiltonians
Authors: Han Zhaoyu , Chen Jing-Yuan
Published: February 2023

Abstract

The Kapustin-Fidkowski no-go theorem forbids U(1) symmetric topological orders with non-trivial Hall conductivity in (2+1)d from admitting commuting projector Hamiltonians, where the latter is the paradigmatic method to construct exactly solvable lattice models for topological orders. Even if a topological order would intrinsically have admitted commuting projector Hamiltonians, the theorem forbids so once its interplay with U(1) global symmetry which generates Hall conductivity is taken into consideration. Nonetheless, in this work, we show that for all (2+1)d U(1) symmetric abelian topological orders of such kind, we can construct a lattice Hamiltonian that is controllably solvable at low energies, even though not “exactly” solvable; hence, this no-go theorem does not lead to significant difficulty in the lattice study of these topological orders. Moreover, for the fermionic topological orders in our construction, we introduce the lattice notion of spin-c structure — a concept important in the continuum that has previously not been adequately introduced in the lattice context.
JT gravity and near-extremal thermodynamics for Kerr black holes in AdS4,5 for rotating perturbations
Authors: Poojary Rohan R.
Published: February 2023

Abstract

We study the near horizon 2d gravity theory which captures the near extremal thermodynamics of Kerr black holes where a linear combination of excess angular momentum δJ and excess mass δM is held fixed. These correspond to processes where both the mass and the angular momenta of extremal Kerr black holes are perturbed leaving them near extremal. For the Kerr AdS4 we hold $$ \delta J-\mathcal{L}\delta M=0 $$
δJ
−
L
δM
=
0
while for Myers-Perry(MP) type Kerr black hole in AdS5 we hold $$ \delta {J}_{\varphi 1,2}-{\mathcal{L}}_{\varphi 1,2}\delta M=0 $$
δ

J

φ
1
,
2

−

L

φ
1
,
2

δM
=
0
. We show that in near horizon, the 2d Jackiw-Teitelboim theory is able to capture the thermodynamics of the higher dimensional black holes at small near extremal temperatures TH. We show this by generalizing the near horizon limits found in literature by parameters $$ \mathcal{L} $$
L
and $$ {\mathcal{L}}_{\varphi 1,2} $$

L

φ
1
,
2

for the two geometries. The resulting JT theory captures the near extremal thermodynamics of such geometries provided we identify the temperature $$ {T}_H^{(2)} $$

T
H

2

of the near horizon AdS2 geometry to be $$ {T}_H^{(2)}={T}_H/\left(1-\mu \mathcal{L}\right) $$

T
H

2

=

T
H

/

1
−
μ
L

for 4d Kerr and $$ {T}_h^2={T}_H/\left(-\mu \left({\mathcal{L}}_{\varphi 1}+{\mathcal{L}}_{\varphi 2}\right)\right) $$

T
h
2

=

T
H

/

−
μ

L

φ
1

+

L

φ
2

for 5d Kerr μ is their chemical potential, with $$ \mu \mathcal{L}<1 $$
μ
L
<
1
and $$ \mu \left({\mathcal{L}}_{\varphi 1}+{\mathcal{L}}_{\varphi 2}\right)<1 $$
μ

L

φ
1

+

L

φ
2

<
1
respectively. We also argue that such a theory embeds itself non-trivially in the higher dimensional theory

dual to the Kerr geometries.
Quantum field theory with ghost pairs
Authors: Liu Jiangfan , Modesto Leonardo , Calcagni Gianluca
Published: February 2023

Abstract

We explicitly show that general local higher-derivative theories with only complex conjugate ghosts and normal real particles are unitary at any perturbative order in the loop expansion. The proof presented here relies on integrating the loop energies on complex paths resulting from the deformation of the purely imaginary paths, when the external energies are continued from imaginary to real values. Contrary to the case of nonlocal theories, where the same integration path was first proposed, for the classes of theories studied here the same procedure is not analytic, but the resulting theory is unitary and unique when the complex ghosts are present in pairs. As an explicit application, a special class of higher-derivative super-renormalizable or finite gravitational and gauge theories turns out to be unitary at any perturbative order if we exclude the complex ghosts from the spectrum of the theory, as it is normally accepted for Becchi-Rouet-Stora-Tyutin (BRST) ghosts. Finally, we propose an analogy between confined gluons in quantum Yang-Mills theory and classical complex pairs in local higher-derivative theories. According to such interpretation, complex ghosts will not appear on shell as asymptotic states because confined in what is natural to name “ghostballs.”
Holographic collisions in large D effective theory
Authors: Luna Raimon , Sanchez-Garitaonandia Mikel
Published: February 2023

Abstract

We study collisions of Gaussian mass-density blobs in a holographic plasma, using a large D effective theory, as a model for holographic shockwave collisions. The simplicity of the effective theory allows us to perform the first 4+1 collisions in Einstein-Maxwell theory, which are dual to collisions of matter with non-zero baryonic number. We explore several collision scenarios with different blob shapes, impact parameters and charge values and find that collisions with impact parameter below the transverse width of the blobs are equivalent under rescaling. We also observe that charge weakly affects the rest of quantities. Finally, we study the entropy generated during collisions, both by charge diffusion and viscous dissipation. Multiple stages of linear entropy growth are identified, whose rates are not independent of the initial conditions.
Infrared phases of 2d QCD
Authors: Delmastro Diego , Gomis Jaume , Yu Matthew
Published: February 2023

Abstract

We derive the necessary and sufficient conditions for a 2d QCD theory of massless gluons and left and right chiral quarks in arbitrary representations of a gauge group G to develop a mass gap. These results are obtained from spectral properties of the lightcone and temporal QCD Hamiltonians. The conditions can be explicitly solved, and we provide the complete list of all 2d QCD theories that have a quantum mechanical gap in the spectrum, while any other theory not in the list is gapless. The list of gapped theories includes QCD models with quarks in vector-like as well as chiral representations. The gapped theories consist of several infinite families of classical gauge groups with quarks in rank 1 and 2 representations, plus a finite number of isolated cases. We also put forward and analyze the effective infrared description of QCD — TQFTs for gapped theories and CFTs for gapless theories — and exhibit several interesting features in the infrared, such as the existence of non-trivial global ’t Hooft anomalies and emergent supersymmetry. We identify 2d QCD theories that flow in the infrared to celebrated CFTs such as minimal models, bosonic and supersymmetric, and Wess-Zumino-Witten and Kazama-Suzuki models.
Aktuelle Möglichkeiten und Herausforderungen bei der Therapie des laryngopharyngealen Refluxes
Authors: Runggaldier Daniel , van Schie Bram , Marti Silvan , Bohlender Jörg E.
Published: February 2023

Der laryngopharyngeale Reflux (LPR) ist durch ein Aufstoßen von gastralem bzw. gastroduodenalem Sekret wie auch von gasförmigem Inhalt in den oberen aerodigestiven Trakt charakterisiert, wodurch eine Schädigung der Schleimhäute u. a. im Larynx- und Pharynxbereich resultieren kann. Eine Reihe von Symptomen wie das klassische retrosternale Brennen und saure Aufstoßen oder weitere, teils sehr unspezifische Symptome wie Heiserkeit, chronischer Husten, zervikales Globusgefühl oder Hypersekretion von Mukus können daraus resultieren. Bei heterogener Studienlage und dem Fehlen eines Goldstandards ist, wie kürzlich zusammengefasst, die Diagnosestellung des LPR schwierig und umstritten. Die Therapieoptionen des LPR werden aufgrund der dünnen Datenlage ebenfalls kontrovers diskutiert und können neben medikamentösen auch konservative diätetische Maßnahmen umfassen. Das Ziel der nachfolgenden Übersichtsarbeit ist daher, die verfügbaren therapeutischen Optionen des LPR kritisch zu diskutieren und für den praktischen klinischen Alltag zusammenzufassen.
Image and video compression of fluid flow data
Authors: Anatharaman Vishal , Feldkamp Jason , Fukami Kai , Taira Kunihiko
Published: February 2023

We study the compression of spatial and temporal features in fluid flow data using multimedia compression techniques. The efficacy of spatial compression techniques, including JPEG and JPEG2000 (JP2), and spatiotemporal video compression techniques, namely H.264, H.265, and AV1, in limiting the introduction of compression artifacts and preserving underlying flow physics are considered for laminar periodic wake around a cylinder, two-dimensional turbulence, and turbulent channel flow. These compression techniques significantly compress flow data while maintaining dominant flow features with negligible error. AV1 and H.265 compressions present the best performance across a variety of canonical flow regimes and outperform traditional techniques such as proper orthogonal decomposition in some cases. These image and video compression algorithms are flexible, scalable, and generalizable holding potential for a wide range of applications in fluid dynamics in the context of data storage and transfer.

Graphic abstract
The alteration of intestinal mucosal α-synuclein expression and mucosal microbiota in Parkinson’s disease
Authors: Shi Jihua , Wang Yiran , Chen Dan , Xu Xue , Li Wenbin , Li Kai , He Jing , Su Wen , Luo Qingfeng
Published: February 2023

Parkinson’s disease (PD) is the second most common neurodegenerative disease but still lacks a preclinical strategy to identify it. The diagnostic value of intestinal mucosal α-synuclein (αSyn) in PD has not drawn a uniform conclusion. The relationship between the alteration of intestinal mucosal αSyn expression and mucosal microbiota is unclear. Nineteen PD patients and twenty-two healthy controls were enrolled in our study from whom were collected, using gastrointestinal endoscopes, duodenal and sigmoid mucosal samples for biopsy. Multiplex immunohistochemistry was performed to detect total, phosphorylate, and oligomer α-synuclein. Next-generation 16S rRNA amplicon sequencing was applied for taxonomic analysis. The results implied that oligomer α-synuclein (OSyn) in sigmoid mucosa of PD patients was transferred from the intestinal epithelial cell membrane to the cytoplasm, acinar lumen, and stroma. Its distribution feature was significantly different between the two groups, especially the ratio of OSyn/αSyn. The microbiota composition in mucosa also differed. The relative abundances of Kiloniellales, Flavobacteriaceae, and CAG56 were lower, while those of Proteobacteria, Gammaproteobacteria, Burkholderiales, Burkholdriaceae, Oxalobacteraceae, Ralstonia, Massilla, and Lactoccus were higher in duodenal mucosa of PD patients. The relative abundances of Thermoactinomycetales and Thermoactinomycetaceae were lower, while those of Prevotellaceae and Bifidobacterium longum were higher in patients’ sigmoid mucosa. Further, the OSyn/αSyn level was positively correlated with the relative abundances of Proteobacteria, Gammaproteobacteria, Burkholderiales, Pseudomonadales, Burkholderiaceae, and Ralstonia in the duodenal mucosa, while it was negatively correlated with the Chao1 index and observed operational taxonomic units of microbiota in sigmoid mucosa. The intestinal mucosal microbiota composition of PD patients altered with the relative abundances of proinflammatory bacteria in the duodenal mucosa increased. The ratio of the OSyn/αSyn level in the sigmoid mucosa indicated a potential diagnostic value for PD, which also correlated with mucosal microbiota diversity and composition.

Key points

• The distribution of OSyn in sigmoid mucosa differed between PD patients and healthy controls.

• Significant alterations in the microbiome were found in PD patients’ gut mucosa.

• OSyn/αSyn level in sigmoid mucosa indicated a potential diagnostic value for PD.
Transmission line modeling co-simulation with distributed delay-size control using steady-state identification
Authors: Braun Robert , Hällqvist Robert , Fritzson Dag
Published: February 2023

Combining performance and numerical stability is a key issue in co-simulation. The Transmission Line Modeling method uses physically motivated communication delays to ensure numerical stability for stiff connections. However, using a fixed communication delay may limit performance for some models. This paper proposes Steady-State Identification for enabling variable communication delays. Three algorithms for online Steady-State Identification are evaluated in three different co-simulation models. All algorithms are able to identify steady state and can thereby determine when communication delays can be allowed to increase without compromising accuracy and stability. The results show a reduction in number of the solver derivative evaluations by roughly 40–60% depending on the model. The proposed method additionally supports connections with asymmetric communication delays, which allows each sub-model to independently control the delay of its input variables. Models supporting delay-size control can thereby be connected to those that do not, so that the step length of each individual sub-model is maximized. Controlling the delay-size in sub-models also makes the method independent of the master co-simulation algorithm.
Surgical management of extrahepatic portal vein obstruction in children: advantages of MesoRex shunt compared with distal splenorenal shunt
Authors: Khamag Omar , Numanoglu Alp , Rode Heinz , Millar Alastair , Cox Sharon
Published: February 2023

Purpose

To review surgical management of extrahepatic portal vein obstruction (EHPVO) at Red Cross War Memorial Children’s Hospital and compare MesoRex shunt (MRS) with distal splenorenal shunt (DSRS).

Methods

This is a single-centre retrospective review documenting pre- and post-operative data in 21 children. Twenty-two shunts were performed, 15 MRS and 7 DSRS, over an 18-year period. Patients were followed up for a mean of 11 years (range 2–18). Data analysis included demographics, albumin, prothrombin time (PT), partial thromboplastin time (PTT), International normalised ratio (INR), fibrinogen, total bilirubin, liver enzymes and platelets before the operation and 2 years after shunt surgery.

Results

One MRS thrombosed immediately post-surgery and the child was salvaged with DSRS. Variceal bleeding was controlled in both groups. Significant improvements were seen amongst MRS cohort in serum albumin, PT, PTT, and platelets and there was a mild improvement in serum fibrinogen. The DSRS cohort showed only a significant improvement in the platelet count. Neonatal umbilic vein catheterization (UVC) was a major risk for Rex vein obliteration.

Conclusion

In EHPVO, MRS is superior to DSRS and improves liver synthetic function. DSRS does control variceal bleeding but should only be considered when MRS is not technically feasible or as a salvage procedure when MRS fails.
Seasonal variations in acute diverticular disease hospitalisations in New Zealand
Authors: Varghese Chris , Wu Zhenqiang , Bissett Ian P. , Connolly Martin J. , Broad Joanna B.
Published: February 2023

Purpose

Seasonal variation of acute diverticular disease is variably reported in observational studies. This study aimed to describe seasonal variation of acute diverticular disease hospital admissions in New Zealand.

Methods

A time series analysis of national diverticular disease hospitalisations from 2000 to 2015 was conducted among adults aged 30 years or over. Monthly counts of acute hospitalisations’ primary diagnosis of diverticular disease were decomposed using Census X-11 times series methods. A combined test for the presence of identifiable seasonality was used to determine if overall seasonality was present; thereafter, annual seasonal amplitude was calculated. The mean seasonal amplitude of demographic groups was compared by analysis of variance.

Results

Over the 16-year period, 35,582 hospital admissions with acute diverticular disease were included. Seasonality in monthly acute diverticular disease admissions was identified. The mean monthly seasonal component of acute diverticular disease admissions peaked in early-autumn (March) and troughed in early-spring (September). The mean annual seasonal amplitude was 23%, suggesting on average 23% higher acute diverticular disease hospitalisations during early-autumn (March) than in early-spring (September). The results were similar in sensitivity analyses that employed different definitions of diverticular disease. Seasonal variation was less pronounced in patients aged over 80 (p = 0.002). Seasonal variation was significantly greater among Māori than Europeans (p < 0.001) and in more southern regions (p < 0.001). However, seasonal variations were not significantly different by gender.

Conclusions

Acute diverticular disease admissions in New Zealand exhibit seasonal variation with a peak in Autumn (March) and a trough in Spring (September). Significant seasonal variations are associated with ethnicity, age, and region, but not with gender.
Erratum to: Head/skull injury potential of empty 0.5-l beer glass bottles vs. 0.33-l Coke bottles
Authors: Nentwig C , Steinhoff S , Adamec J , Kunz SN
Published: February 2023

In the context of further impact tests with various striking weapons against the skull, it turned out that the manufacturer had incorrectly calibrated the force measuring plate, which was used in our earlier experiments. When the tests were carried out again under the same conditions, the measurement results were significantly higher.
Dopamine transporter single photon emission computed tomography (DaT-SPECT) use in the diagnosis and clinical management of parkinsonism: an 8-year retrospective study
Authors: Tsang Kaki , Walker Richard
Published: February 2023

Introduction

Parkinson’s disease (PD) is a neurodegenerative movement disorder that is typically diagnosed clinically. DaT-SPECT scanning (DaT Scan) can be used when there is diagnostic difficulty differentiating from non-neurodegenerative Parkinsonism. This study assessed the effect of DaT Scan imaging on diagnosis and subsequent clinical management of these disorders.

Methods

This single-trust retrospective study involved 455 patients who had undergone DaT scans for investigation for Parkinsonism, between 01/01/2014 and 31/12/2021. Data collected included patient demographics, date of clinical assessment, scan report, pre-scan and post-scan diagnosis, and clinical management.

Results

The mean age at scan was 70.5 years and 57% were male. The percentage of patients who had an abnormal scan result was 40% (n = 184), whilst 53% (n = 239) had a normal scan result, and 7% (n = 32) had an equivocal scan. Pre-scan diagnosis was consistent with scan results in 71% of cases of neurodegenerative Parkinsonism, whereas this figure was 64% for cases of non-neurodegenerative Parkinsonism. For all DaT scans, the diagnosis was changed in 37% of patients (n = 168), whilst the clinical management was changed in 42% of patients (n = 190). Change in management involved 63% starting dopaminergic medication, 5% stopping dopaminergic medications, and 31% undergoing other changes in management.

Conclusion

DaT imaging is useful for confirming the correct diagnosis and clinical management for patients with clinically indeterminate Parkinsonism. Pre-scan diagnoses were generally consistent with scan results.
Influence of the body positions adopted for resistance training on intraocular pressure: a comparison between the supine and seated positions
Authors: Lara Paula M. , Redondo Beatriz , Jerez-Mayorga Daniel , Martínez-García Dario , García-Ramos Amador , Vera Jesús
Published: February 2023

Objectives

A variety of factors are known to mediate on the intraocular pressure (IOP) response to resistance training. However, the influence of the body position adopted during resistance training on IOP remain unknown. The objective of this study was to determine the IOP response to the bench press exercise at three levels of intensity when performed in supine and seated positions.

Methods

Twenty-three physically active healthy young adults (10 men and 13 women) performed 6 sets of 10 repetitions against the 10-RM (repetition maximum) load during the bench press exercise against three levels of intensity (high intensity: 10-RM load; medium intensity: 50% of the 10-RM load; and control: no external load) and while adopting two different body positions (supine and seated). A rebound tonometer was employed to measure IOP in baseline conditions (after 60 s in the corresponding body position), after each of the 10 repetitions, and after 10 s of recovery.

Results

The body position adopted during the execution of the bench press exercise significantly affected the changes in IOP (p < 0.001, ηp2 = 0.83), with the seated position providing lower increases in IOP levels compared to the supine position. There was an association between IOP and exercise intensity, with greater IOP values in the more physically demanding conditions (p < 0.001, ηp2 = 0.80).

Conclusions

The use of seated positions, instead of supine positions, for the execution of resistance training should be prioritized for maintaining more stable IOP levels. This set of findings incorporates novel insights into the mediating factors on the IOP response to resistance training. In future studies, the inclusion of glaucoma patients would allow to assess the generalizability of these findings.