bluuebunny/crossref_metadata_2025 huggingface dataset:
Numerical investigation of multi-designed mufflers in internal combustion engines for noise reduction
Authors: Adibi Tohid , Razavi Seyed Esmail , Hassanpour Hussein , Ahmed Shams Forruque , Shah Nehad Ali
Published: October 2023

Some of the most harmful sources of noise pollution to humans are the exhaust gases of internal combustion engines and factory equipment such as compressors and turbines. An environment contaminated by these sounds can also cause brain cancer. These noise issues can be addressed by installing expansion chambers in the exhaust path. Although numerous studies have been conducted on mufflers, three-dimensional mufflers with non-coaxial inlet and outlet dimensions have not been emphasized in previous studies. To improve the acoustic attenuation performance of the reactive muffler, the effects of different parameters on transmission loss need to be investigated, which is performed in the present paper. The geometry of the muffler was considered one of the noise control parameters. The muffler was modeled using the Helmholtz equation and simulated in COMSOL for analysis. The results demonstrate that the noise level drops with an increase in length, width, and height. The optimal values for the length, width, and height of the muffler are calculated to be 700, 320, and 170 mm, respectively. In addition, the optimum size of the non-coaxial muffler is found 60 mm. Compared to existing mufflers, the proposed muffler reduces noise by 13% to 34%. These research findings will assist the automotive or other related industries to reduce the noise produced by vehicles and other industrial devices.
Comparing the loss of charge carrier generation with the loss of V
OC at low temperatures in organic bulk-heterojunction blends
Authors: Wilson N M , Aarnio H , Österbacka R
Published: October 2023

We estimate the temperature dependence of charge carrier generation in P3HT:ICBA and PTB7:PCBM using continuous-wave photoinduced absorption. For P3HT:ICBA, the generation rate increases fivefold from 79 K to ca 250 K, above which it saturates. We compare this to the temperature dependence of open-circuit voltage (V
OC) which at low temperatures shows a decrease with decreasing temperatures, in disagreement with the typically expected linear rise. This voltage loss is too large to be explained by the decrease of generation with decreasing temperature. For PTB7:PCBM the dominant species has a generation rate increasing from 90 to 150 K, after which it decreases. For PTB7:PCBM there is no decrease in V
OC at low temperatures. Our findings support the lack of correlation between the decrease in V
OC and a decrease in generation rate. We conclude that the loss of V
OC does not originate in charge carrier dynamics in the bulk material, but is due to contact effects.
A comparison of wear between unidirectional and reciprocating sliding motions under different applied loads and lubricants
Authors: Liu Guojuan , Li Xia , Li Yuting , Li Yuan , Cao Cheng , Wang Zhaohua , Li Hao , Zhu Minhao
Published: October 2023

Exploring the wear mechanisms of tribo-pairs is essential to reducing friction and wear. Although it has been known that the wear mechanisms between reciprocating sliding motion (RSM) and unidirectional sliding motion (USM) are different, the differences are seldom reported, which causes trouble for many researchers in selecting proper tribo-pairs or wear test methods. Herein, we systematically explore the effect of RSM and USM on the wear mechanism for several typical friction and lubricant materials, such as alloys, liquids, and solid lubricants. It is found that tribo-pairs suffer unstable sliding under RSM, and sliding speed as well as sliding direction change frequently, which makes it difficult to form a transfer layer or tribo-chemical reaction film, leading to high friction and abrasive wear for hard alloys and DLC coating. Additionally, the quasi-static stage under RSM, when lubricated with polyalphaolefin (PAO) 40, does not facilitate elastohydrodynamic (EHD) lubrication, which typically prevents wear. However, stable sliding under USM could lead to adhesive wear, increasing the friction coefficient for soft TC4 alloys. Although wear under RSM is generally higher than that under USM, increasing the applied load could diminish the wear difference for hard metals.
Flow Characteristic Study on Wake Flow of High-speed vehicles
Authors: Zhou Guiyu , Zhang Jie , Yang Yueyue , Chen Hongyang , Mo Tao , Liu Liang , Jia Chuan , Jiang Anlin , Chen JianJun , Cui Pengcheng
Published: October 2023

Based on the general CFD software NNW-FlowStar of national numerical wind tunnel engineering, this paper adopts anisotropic unstructured hybrid mesh to simulate the wake field characteristics of aircraft in high-speed flight. NNW-FlowStar software in high resolution numerical format, gaussian type node gradient calculation method, massively parallel and a series of numerical algorithm in terms of development and improvement to ensure the fine simulation of the hypersonic flow field. The numerical method can clearly aircraft wake flow field, the main shock, the corner expansion area, shear layer and the shock wave, clearly shows the wake flow field structure. With the increase of Mach number, the wake flow is getting more and more strong, the backwater area range is more and more small, after the stagnation point, the shock wave is also much greater compressibility.
A fractional derivative aerodynamic model at high angles of attack
Authors: Yu Jing , Wu Xiaojun , Liu Shenshen , Kong Yinan , Hao Dong
Published: October 2023

A fractional derivative aerodynamic model is put forward based on Grünwald-Letnikov fractional derivative in this paper. In order to express the hysteresis property of aerodynamic coefficients, a fractional derivative state-space equation is developed from Goman’s differential equation. A fast and high-accuracy calculation method of Grünwald-Letnikov fractional derivative is proposed. Then, the model is demonstrated by several experiments data from literatures. The simulation results show that the presented fractional derivative aerodynamic model can preferably express the nonlinear unsteady aerodynamic characteristics of airfoils and aircrafts. The proposed modelling framework is meaningful to the designation of flight and control system.
Experimental study on wake interference characteristics of horizontal-axis wind turbine
Authors: Li Bingbing , Cai Gaoyuan , Zhang Yiheng , Liu Liqun , Zhang Zhenpeng , Zhang Huiguang
Published: October 2023

To investigate the flow field distribution under the interference of multiple wind turbine wakes, two different types of ground-based LiDARs were used to conduct wind measurement experiments in a wind farm. Taking the wake field distribution characteristics of two wind turbines as an example, combined with wind measurement data, the complex wake interference flow field is classified into three typical interference conditions: non-wake, partial wake and full wake. And the wake development characteristics under the above three wake conditions are quantitatively analyzed. The results show that under the condition of non-wake interference, the wakes are independent of each other, the wake recovery rate is basically the same. Under partial wake and full wake interference conditions, the wake center recovery rate of the downstream wind turbine decreases, and the wake recovery rate drops most obviously under the full wake interference condition.
A fast evaluation method of surrogate model based on active subspace dimension reduction
Authors: Lv Luogeng , Liu Xiao , Hu Xingzhi , Zhang Chao , Chen Jiangtao
Published: October 2023

Aimed at the problem of high-dimensional uncertainty quantification commonly existing in engineering complex shapes, traditional methods are often time-consuming and energy-consuming. So the paper proposes an efficient surrogate model method based on active subspace dimension reduction. The method uses active subspace to achieve feature dimension reduction and construct surrogate model, and develops a fast evaluation method of 1-D active subspace based on polynomial least squares decomposition to solve the difficult derivative problems. The detailed implementation process of the method is given in the paper, and the feasibility of the method is verified by examples such as the ablation thermal response and RAE2822 airfoil. It provides a solution for the quantification of multivariate uncertainty in engineering.
Hierarchical structure analysis in verification and validation of aerodynamic numerical simulation
Authors: Zhang Chao , Shen Yingying , Xiao Wei
Published: October 2023

Verification and validation is a basic way to ensure the credibility of numerical simulation. The realization of verification and validation of aerodynamic numerical simulation requires scientific and rigorous processes. At present, long-term research on verification and validation at home and abroad has summarized the whole verification and validation process into four stages: problem analysis, verification, validation and credibility evaluation. In each stage, it is of great significance to use the hierarchical structure to sort out key information and clarify tasks. This paper summarizes the application of hierarchical structure in the verification and validation process, and gives examples of aerodynamic numerical simulation with application value.
Numerical Study of the Pin Fin Types on Combustion Characteristics of Micro Combustor
Authors: He Ziqiang , Zhang Lei , Huang Song , Wang Fei , Zhang Longyi , Lv Xiao , Li Xiuquan
Published: October 2023

The influence of different shapes of pin fin arrays in micro combustors on combustion performance is investigated numerically. All the micro combustors show a high combustion efficiency and the one with triangle-B pin fin arrays exhibits superiority in combustion efficiency. Additionally, the combustor efficiency of all micro combustors is relatively low and reduces as the velocity increases. This works provides a great reference and guidance for the development of the micro burner in MTPV system.
Study on Hydrogen Flow and Heat Transfer in Underground Salt Cavern Hydrogen Storage
Authors: Zhang Yi , Yang Lihong , Huang Wei
Published: October 2023

Hydrogen energy is a green, low-carbon, widely used secondary energy with abundant sources, and is gradually becoming one of the important carriers of energy transformation. The safe and efficient storage of hydrogen energy is particularly important. Underground hydrogen storage technology has received widespread attention due to its large scale and low comprehensive cost. Salt cavern hydrogen storage has good sealing performance, stable structure, and flexible operation, making it the most promising choice for large-scale underground hydrogen storage. According to the thermodynamic characteristics of hydrogen, a heat transfer model of hydrogen flow in salt cavern hydrogen storage is established. Three operating conditions, namely, hydrogen injection, static state, and hydrogen production, are simulated and calculated, and the flow field characteristics of hydrogen under different operating conditions are determined, providing technical support for the research on the design of hydrogen injection and production schemes for salt cavern hydrogen storage.
Research on the engineering application of leakage diffusion theory based on finite volume method in LNG pipeline
Authors: Zeng Chunlei , Gao Yuan
Published: October 2023

In order to provide theoretical reference for the volume design of the terminal sump, this paper analyses the physical process of leakage and evaporation at the LNG terminal using. Combined with the theory of orifice leakage and evaporation diffusion and the actual project scenario, the corresponding mathematical model is given. From qualitative analysis, the main factors affecting LNG leakage and evaporation diffusion are given. The mathematical model is applied to engineering practice, and a large number of calculations are carried out to give the quantitative relationship between leakage, evaporation and diffusion and various influencing factors. Through research, it is found that the leakage of LNG is far greater than the evaporation on the wharf. When designing the volume of the sump, the evaporation of LNG on the wharf can be ignored. According to the leakage model of the pipeline orifice, the credible leakage volume in line with the actual project can be obtained.
Simulation study on flow and response temperature of armored vehicle in low temperature environment test
Authors: Liu Zhenting , Zhang Baojun , Wang Guohong , Li Shuang
Published: October 2023

In this paper, three-dimensional CFD simulation and vehicle’s environmental test were combined, according to the size and operating parameters of the actual environmental test chamber, a model of the low-temperature environmental test chamber was constructed by using 3D modeling software; by removing the structure that has little influence on the process of environmental experiment, a three-dimensional vehicle model suitable for simulation calculation is built, and by means of 3D model assembly, the combination of vehicle and environmental chamber model is realized. According to the low temperature environment test conditions, CFD numerical simulation method was used to analyze the flow velocity distribution in the test chamber and the response trend of each chamber to the low temperature environment, the results were also compared with the experimental data of low temperature environment, which provides a theoretical basis for carrying out simulation and prediction research based on digital environment test.
Effect analysis of centrifugal pump parameters optimization design on performance
Authors: Sun Xiaoyan , Zhu Rensheng , Wang Jiangjie , Li Yuan
Published: October 2023

Under the background of energy-saving priority and efficient use of energy, centrifugal pump, as a kind of energy conversion equipment in modern industry and agriculture with liquid as the medium, plays an important role in many occasions. Optimization of performance parameters of centrifugal pump can improve efficiency and save energy. Important parameters include the number of blades and structural optimization of blade tail, etc. These parameters are often selected according to experience in actual production, which lacks accuracy and persuasiveness. The influence of different blade numbers and structural designs on cavitation performance and efficiency of the pump is studied, and the characteristic curve of the pump is drawn. The blade performance is evaluated comprehensively according to the pressure distribution, flow condition, cavitation degree and velocity diagram under different blade numbers, and the conclusion is drawn. The efficiency of the four-blade pump is 6.96% higher than that of the original six-blade pump, 1.96% higher than that of the three-blade pump, and 5.11% higher than that of the five-blade pump. The optimization results are obvious, which provides reference for the determination and setting of the number of centrifugal pumps.
Experimental study on vibration and noise of throttle valve in water-conveying systems
Authors: Qin Ziming , Cai Biaohua , Xiao Longzhou
Published: October 2023

In the water conveying system, the throttle valve has a great impact on the vibration and noise, which needs to be controlled. In this paper, a noise test bench for throttle valve in water conveying system is established. The vibration, air noise and flow noise are measured under different pressure differences and flow rates for throttle valves with different structures and diameters. The results show that the throttle valve vibration and air noise increase with the increase of pressure difference and flow when the noise is above 70 dB(A). When the pressure difference is more than 0.5MPa, the flow noise of ordinary ball valve is mainly in the high frequency range. The vibration, noise and pipeline flow noise of the low-noise valve with multistage throttling are significantly reduced, and the flow noise is mainly in the low frequency band below 315Hz. The pipe flow noise in front of the throttle valve is broadband which decreases with the increase of frequency. Increasing the pressure behind the throttle valve can reduce the valve vibration under the same pressure difference.
Shape optimization of the spillway approach channel of Baleh Hydropower Project based on numerical simulation
Authors: Zhang Wenjiao , Hu Nengming , Yang Yiyi , Wang Zhongmei , Zhao Xing
Published: October 2023

Baleh Hydropower Project has a protruding headland between the spillway inlet and the power intake structure. Based on the results of the model tests, the velocity gradient near the protruding headland under high flow conditions is large and an unstable vortex occurs. To address the unfavorable flow problems of the original spillway approach channel, this paper simulates the original spillway approach channel using a three-dimensional turbulence numerical model and verifies it with the model tests, and provides numerical simulation results for two optimized cases: excavation and backfilling. The calculation results show that both backfilling and excavation optimization cases improve the right side flow pattern, the unstable vortex disappears, and the flow between the approach channel and the spillway inlet is smoother than the original design. Comparing the two optimized cases, the average flow velocity in the upstream section of the approach channel of the excavation case is reduced, but the flow velocity near the right bank of the approach channel close to the spillway gate bay inlet becomes larger, and the average flow velocity of the excavation modified case is more unevenly distributed.
Nanofilm-enhanced electrochemical DNA sensing: a breakthrough for yellow rust detection in wheat
Authors: Rehsawla Rizwana , Dhull Nidhi , Tomar Monika , Sharma Savita , Yadav Neelam R
Published: October 2023

This study showcases the development of a genosensor utilizing a nanoscale NiO thin film. The genosensor is constructed on a glass substrate coated with tin-doped indium oxide (ITO) and is designed for the specific detection of DNA sequences associated with Puccinia striiformis f. sp. tritici (Pst), the causal agent of wheat yellow rust. The detection process relies on the utilization of methylene blue (MB) as an electrochemical indicator, with NiO acting as the matrix and the electrochemical measurement system serving as the transducer. Various single-stranded DNA oligonucleotide sequences related to Pst pathogenesis are employed as probes to enable sensing. The electrochemical response of the nanoscale bioelectrode is characterized and studied using two distinct electrochemical techniques, cyclic voltammetry (CV) and differential pulse voltammetry (DPV), in conjunction with a potentiostat. The detection ranges spans from 40 pg μl−1 to 115 ng μl−1, demonstrating a linear correlation with exceptional precision. The absence of DNA-based biosensors for the detection of Puccinia striiformis f. sp. tritici (Pst) has prompted the need for a new method to address the limitations associated with previously reported technologies. Although surface plasmon resonance (SPR) immunoassays have been reported for Pst detection, the development of DNA-based biosensors specifically tailored for Pst detection remains unexplored. Introducing a novel method aims to overcome the challenges and shortcomings of existing techniques, providing a new approach to detect and combat the devastating effects of Pst on wheat crops. By leveraging the advantages of DNA-based biosensors, such as their sensitive and precise detection capabilities, this new method seeks to enhance the accuracy and efficiency of Pst detection, ultimately contributing to the development of effective strategies for disease management and crop protection. The developed nanoscale electrochemical DNA sensor offers outstanding sensitivity, extended shelf life, and reliable recovery, effectively minimizing the likelihood of obtaining erroneous results. A significant highlight of this study is the first-time utilization of conserved sequences associated with pathogenesis in selected Pst strains for the development of a nanoscale genosensor.
Travelling waves in nonlinear lattices
Authors: Fečkan Michal
Published: October 2023

We present our recent results on travelling wave solutions for differential equations on lattices modeled by metamaterials, discrete nonlinear Schrödinger equations, Fermi-Pasta-Ulam models, and fractional differential equations on lattices. Both local and nonlocal couplings are considered. The obtained results are rather broad and various.
Bundles of Weyl structures and invariant calculus for parabolic geometries
Authors: Čap Andreas , Slovák Jan
Published: October 2023

For more than hundred years, various concepts were developed to understand the fields of geometric objects and invariant differential operators between them for conformal Riemannian and projective geometries. More recently, several general tools were presented for the entire class of parabolic geometries, i.e., the Cartan geometries modelled on homogeneous spaces

G

/

P

G/P

with

P
P

a parabolic subgroup in a semi-simple Lie group

G
G

. Similarly to conformal Riemannian and projective structures, all these geometries determine a class of distinguished affine connections, which carry an affine structure modelled on differential 1-forms

Υ
\Upsilon

. They correspond to reductions of

P
P

to its reductive Levi factor, and they are called the Weyl structures similarly to the conformal case. The standard definition of differential invariants in this setting is as affine invariants of these connections, which do not depend on the choice within the class. In this article, we describe a universal calculus which provides an important first step to determine such invariants. We present a natural procedure how to construct all affine invariants of Weyl connections, which depend only tensorially on the deformations

Υ
\Upsilon

.
Coverings and pseudosymmetries of differential equations
Authors: Chetverikov Vladimir
Published: October 2023

Finite-dimensional coverings from systems of differential equations are investigated. This problem is of interest in view of its relationship with the computation of differential substitutions, nonlocal symmetries, recursion operators, and Bäcklund transformations. We show that the distribution specified by the fibers of a covering is determined by an integrable pseudosymmetry of the system. Conversely, every integrable pseudosymmetry of a system defines a covering from this system. The vertical component of the pseudosymmetry is a matrix analog of the evolution differentiation. The corresponding generating matrix satisfies a matrix analog of the linearization of the equation. A method for constructing coverings is given and demonstrated by the examples of the Laplace equation and the Kapitsa pendulum system.
Graphical posterior predictive classification: Bayesian model averaging with particle Gibbs
Authors: Pavlenko Tatjana , Rios Felix
Published: October 2023

In this study, we present a multi-class graphical Bayesian predictive classifier that incorporates the uncertainty in the model selection into the standard Bayesian formalism. For each class, the dependence structure underlying the observed features is represented by a set of decomposable Gaussian graphical models. Emphasis is then placed on theBayesian model averagingwhich takes full account of the class-specific model uncertainty by averaging over the posterior graph model probabilities. An explicit evaluation of the model probabilities is well known to be infeasible. To address this issue, we consider the particle Gibbs strategy of J. Olsson, T. Pavlenko, and F. L. Rios [Electron. J. Statist. 13 (2019), no. 2, 2865–2897] for posterior sampling from decomposable graphical models which utilizes the so-calledChristmas tree algorithmof J. Olsson, T. Pavlenko, and F. L. Rios [Stat. Comput. 32 (2022), no. 5, Paper No. 80, 18] as proposal kernel. We also derive a strong hyper Markov law which we call thehyper normal Wishart lawthat allows to perform the resultant Bayesian calculations locally. The proposed predictive graphical classifier reveals superior performance compared to the ordinary Bayesian predictive rule that does not account for the model uncertainty, as well as to a number of out-of-the-box classifiers.
Test for mean matrix in GMANOVA model under heteroscedasticity and non-normality for high-dimensional data
Authors: Yamada Takayuki , Himeno Tetsuto , Tillander Annika , Pavlenko Tatjana
Published: October 2023

This paper develops a unified testing methodology for high-dimensional generalized multivariate analysis of variance (GMANOVA) models. We derive a test of the bilateral linear hypothesis on the mean matrix in a general scenario where the dimensions of the observed vector may exceed the sample size, design may be unbalanced, the population distribution may be non-normal and the underlying group covariance matrices may be unequal. The suggested methodology is suitable for many inferential problems, such as the one-way MANOVA test and the test for multivariate linear hypothesis on the mean in the polynomial growth curve model. As a key component of our test procedure, we propose a bias-corrected estimator of the Frobenius norm of the mean matrix. We derive null and non-null asymptotic distributions of the test statistic under a general high-dimensional asymptotic framework that allows the dimensionality to arbitrarily exceed the sample size of a group. The accuracy of the proposed test in a finite sample setting is investigated through simulations conducted for several high-dimensional scenarios and various underlying population distributions in combination with different within-group covariance structures. For a practical demonstration we consider a daily Canadian temperature dataset that exhibits group structure, and conclude that the interaction of latitude and longitude has no effect to predict the temperature.
On geometric convergence for the Metropolis-adjusted Langevin algorithm under simple conditions
Authors: Oliviero-Durmus Alain , Moulines Éric
Published: October 2023

While the Metropolis-adjusted Langevin algorithm is a popular and widely used Markov chain Monte Carlo method, very few papers derive conditions that ensure its convergence. In particular, to the authors’ knowledge, assumptions that are both easy to verify and guarantee geometric convergence, are still missing. In this work, we establish V-uniformly geometric convergence for the Metropolis-adjusted Langevin algorithm under mild assumptions about the target distribution. Unlike previous work, we only consider tail and smoothness conditions for the potential associated with the target distribution. These conditions are quite common in the Markov chain Monte Carlo literature. Finally, we pay special attention to the dependence of the bounds we derive on the step size of the Euler–Maruyama discretization, which corresponds to the proposed Markov kernel of the Metropolis-adjusted Langevin algorithm.
Enantiospecific response of Ips avulsus (Coleoptera: Curculionidae: Scolytinae) to ipsdienol depends on semiochemical context
Authors: Queffelec Joséphine , Gaudon Justin M , Miller Daniel R , McKenney Jessica L , Allison Jeremy D
Published: October 2023

Colonization of hosts by bark beetles is generally mediated by aggregation pheromones. Species competing for the same resource can limit interspecific interactions and maintain reproductive isolation by using different pheromones. In the southern United States, 3 sympatric species of Ips breed in pine hosts, each with a different pheromone blend. Ips avulsus (Eichhoff) uses ipsdienol and lanierone; Ips calligraphus (Germar) uses ipsdienol, cis-verbenol, and trans-verbenol; and Ips grandicollis (Eichhoff) uses ipsenol. Different species can also minimize cross-attraction by using different enantiomeric ratios of the same pheromones. Studies on the enantiomeric ratio of ipsdienol used by I. avulsus have come to contradictory conclusions in part because of geographic and seasonal variation. There is growing evidence that semiochemical context, in the form of different co-baits used in trapping experiments, may also play a role in the responses of I. avulsus to enantiomeric ratios of ipsdienol. We conducted a trapping study at 2 locations with traps baited with (+)-ipsdienol or racemic ipsdienol and co-baited with ipsenol, lanierone, or both ipsenol and lanierone. We found context-dependent effects of both lanierone and ipsenol on the response of I. avulsus to ipsdienol. We suggest that responses to different bait and co-bait combinations may have been shaped by different types of interactions such as the absence of conspecifics or a related species, or the presence of beneficial or antagonistic interspecific interactions.
Exploring Australian children’s perceptions of a school-provided lunch model using a story completion method
Authors: Coulls Elena , Middleton Georgia , Velardo Stefania , Johnson Brittany J
Published: October 2023

Children in Australia currently bring a packed lunch to school from home. Many children are not consuming a healthy diet at school. There is interest from key stakeholders (e.g. education and the non-government sector, food service and parents/caregivers) to transform the Australian system to a school-provided model to improve children’s diets, reduce parental burden and address food insecurity. To facilitate a successful transition to this system, it is important to consider the views of the children. We aimed to explore Australian primary school children’s perceptions of a hypothetical school-provided lunch model. To achieve this aim, we undertook a qualitative study using the story completion method. Twenty-one grade-five children, from one public primary school in South Australia, participated in a once-off data collection session. Children were given a brief story stem and asked to complete a story about a hypothetical school-provided lunch scenario. The story data were analysed using thematic analysis. Four main themes were generated: the eating environment, the food provided, processes of the mealtime and time. The desire for choice was an additional overarching theme that cut across all themes. Our study provides the first exploration of South Australian children’s perceptions of hypothetical school-provided meals. These insights can be used to co-design an acceptable school food system with children to create a positive eating environment that supports healthy eating habits they can carry forward into adulthood.
Singular spectrum analysis (SSA) based hybrid models for emergency ambulance demand (EAD) time series forecasting
Authors: Wang Jing , Peng Xuhong , Wu Jindong , Ding Youde , Ali Barkat , Luo Yizhou , Hu Yiting , Zhang Keyao
Published: October 2023

Accepted by: Konstantinos Nikolopoulos

One of the challenges of emergency ambulance demand (EAD) time series prediction lies in their non-stationary nature. We study this important problem and propose two hybrid forecasting models, which combine the singular spectrum analysis (SSA) time-series technique with autoregressive integrated moving average (ARIMA) parameterized multivariate forecasting. Both daily and hourly time series are studied. The non-stationary time series are decomposed into three eigentriples by SSA: trends, periodic components and residuals. Selection of the group boundary point of the periodic component is a key issue in the SSA method. We use spectrum analysis to compute a threshold for maximum information content of periodic components. ARIMA mean value prediction models are employed to forecast the trends, periodic components and residuals sub-series. Our research compares ARIMA and SSA-based hybrid models by considering the emergency dispatching departure records of six core districts in Guangzhou city from 1 January 2021 to 31 December 2021. Results show that the integrated SSA-ARIMA model performs best. SSA is a very effective pre-processing method for non-stationary time series prediction. The predictive accuracy of using a hybrid model for hourly EAD time series is higher than that for daily ones. Our discussion should be useful for improving EAD prediction in contexts others than that considered in our research.
Radiotracer Development for Fungal-Specific Imaging: Past, Present, and Future
Authors: Lai Jianhao , Wang Benjamin , Petrik Milos , Beziere Nicolas , Hammoud Dima A
Published: October 2023

Invasive fungal infections have become a major challenge for public health, mainly due to the growing numbers of immunocompromised patients, with high morbidity and mortality. Currently, conventional imaging modalities such as computed tomography and magnetic resonance imaging contribute largely to the noninvasive diagnosis and treatment evaluation of those infections. These techniques, however, often fall short when a fast, noninvasive and specific diagnosis of fungal infection is necessary. Molecular imaging, especially using nuclear medicine-based techniques, aims to develop fungal-specific radiotracers that can be tested in preclinical models and eventually translated to human applications. In the last few decades, multiple radioligands have been developed and tested as potential fungal-specific tracers. These include radiolabeled peptides, antifungal drugs, siderophores, fungal-specific antibodies, and sugars. In this review, we provide an overview of the pros and cons of the available radiotracers. We also address the future prospects of fungal-specific imaging.
Evaluating the Performance of Pathogen-Targeted Positron Emission Tomography Radiotracers in a Rat Model of Vertebral Discitis-Osteomyelitis
Authors: Parker Matthew F L , López-Álvarez Marina , Alanizi Aryn A , Luu Justin M , Polvoy Ilona , Sorlin Alexandre M , Qin Hecong , Lee Sanghee , Rabbitt Sarah J , Pichardo-González Priamo A , Ordonez Alvaro A , Blecha Joseph , Rosenberg Oren S , Flavell Robert R , Engel Joanne , Jain Sanjay K , Ohliger Michael A , Wilson David M
Published: October 2023

Background

Vertebral discitis-osteomyelitis (VDO) is a devastating infection of the spine that is challenging to distinguish from noninfectious mimics using computed tomography and magnetic resonance imaging. We and others have developed novel metabolism-targeted positron emission tomography (PET) radiotracers for detecting living Staphylococcus aureus and other bacteria in vivo, but their head-to-head performance in a well-validated VDO animal model has not been reported.

Methods

We compared the performance of several PET radiotracers in a rat model of VDO. [11C]PABA and [18F]FDS were assessed for their ability to distinguish S aureus, the most common non-tuberculous pathogen VDO, from Escherichia coli.

Results

In the rat S aureus VDO model, [11C]PABA could detect as few as 103 bacteria and exhibited the highest signal-to-background ratio, with a 20-fold increased signal in VDO compared to uninfected tissues. In a proof-of-concept experiment, detection of bacterial infection and discrimination between S aureus and E coli was possible using a combination of [11C]PABA and [18F]FDS.

Conclusions

Our work reveals that several bacteria-targeted PET radiotracers had sufficient signal to background in a rat model of S aureus VDO to be potentially clinically useful. [11C]PABA was the most promising tracer investigated and warrants further investigation in human VDO.
The Promise of Molecular Imaging: Focus on Central Nervous System Infections
Authors: Shah Swati , Turner Mitchell L , Chen Xueyi , Ances Beau M , Hammoud Dima A , Tucker Elizabeth W
Published: October 2023

Central nervous system (CNS) infections can lead to high mortality and severe morbidity. Diagnosis, monitoring, and assessing response to therapy of CNS infections is particularly challenging with traditional tools, such as microbiology, due to the dangers associated with invasive CNS procedures (ie, biopsy or surgical resection) to obtain tissues. Molecular imaging techniques like positron emission tomography (PET) and single-photon emission computed tomography (SPECT) imaging have long been used to complement anatomic imaging such as computed tomography (CT) and magnetic resonance imaging (MRI), for in vivo evaluation of disease pathophysiology, progression, and treatment response. In this review, we detail the use of molecular imaging to delineate host-pathogen interactions, elucidate antimicrobial pharmacokinetics, and monitor treatment response. We also discuss the utility of pathogen-specific radiotracers to accurately diagnose CNS infections and strategies to develop radiotracers that would cross the blood-brain barrier.
Maternal nutrient restriction during late gestation reduces vigor and alters blood chemistry and hematology in neonatal beef calves
Authors: Wichman Lindsey G , Redifer Colby A , Meyer Allison M
Published: October 2023

Fall-calving primiparous beef females [body weight: 451 ± 28 (SD) kg; body condition score: 5.4 ± 0.7] were individually-fed either 100% (control; CON; n = 13) or 70% (nutrient restricted; NR; n = 13) of metabolizable energy and metabolizable protein requirements for maintenance, pregnancy, and growth from day 160 of gestation to parturition. Calves were reared naturally by their dams and monitored for latency times from birth to first sternal recumbency, attempt to stand, and stand; vigor scores were assigned at 2, 5, 10, and 20 min of age. Rectal temperatures and jugular blood were obtained at 0 (pre-suckling), 6, 12, 24, and 48 h of age, and blood chemistry, hematology, cortisol, and insulin were determined. Data were analyzed with fixed effects of late gestational nutritional plane (single data point) or nutritional plane, hour, and their interaction (data over time, repeated measures). Calving date was a fixed effect; calf sex was included when P < 0.25. We previously reported that late gestational nutritional plane did not affect gestation length or calf size at birth, but calving assistance and fetal malpresentation occurred more often in NR. Nutritional plane did not affect (P = 0.65) duration of parturition, but calves born to NR dams had slower times to attempt to stand (P = 0.09), slower times to stand (P = 0.02), and poorer 20 min vigor scores (P = 0.05). Serum immunoglobulin G and A concentrations at 48 h were greater (P ≤ 0.03) for NR calves. Rectal temperature of NR calves was less (P = 0.02) at 0 h, but greater (P = 0.04) at 24 h compared with CON. Circulating glucose, non-esterified fatty acids, triglycerides, cortisol, and insulin were not affected by nutritional plane (P ≥ 0.18). Total protein and globulin from 6 to 48 h were greater (P ≤ 0.02) in NR calves. Calves from NR dams had greater (P ≤ 0.08) gamma-glutamyl transferase at 6, 12, and 48 h. Serum aspartate aminotransferase was greater (P ≤ 0.07) from 0 to 24 h and creatine kinase was greater (P ≤ 0.04) from 6 to 24 h in NR calves. At 0 h, potassium was greater (P = 0.03) in NR calves. Calves born to CON had greater chloride (P = 0.08; main effect), sodium (P ≤ 0.09) from 0 to 48 h, and anion gap (P = 0.02) at 6 h. Hematocrit from 6 to 24 h and red blood cells and hemoglobin at 6 and 12 h were greater (P ≤ 0.09) in CON calves. These data indicate that nutrient restriction during late gestation resulted in less vigorous calves with more indicators of trauma in early life.
Regulatory effects of circular RNA on hypoxia adaptation in chicken embryos
Authors: Chen Xuejiao , Zhang Ying , Zhang Wenhui , Nie Ruixue , Bao Haigang , Zhang Bo , Zhang Hao
Published: October 2023

The Tibetan chicken, a native breed of the Tibetan plateau, is adapted to the high-altitude and hypoxic environment of the plateau. As endogenous molecules, circular RNAs (circRNAs) have been shown to play an important role in the adaptation to hypoxic environments and regulation of angiogenesis. In this study, highland Tibetan and lowland Chahua chicken eggs were incubated in a hypoxic environment and the chorionic allantoic membrane was collected for Ribo-Zero RNA sequencing. A total of 1,414 circRNAs, mostly derived from exons, were identified. Of these, 93 differentially expressed circRNAs were detected between Tibetan and Chahua chickens. Combined with the differentially expressed miRNAs and mRNAs identified in our previous study, we identified four circRNAs (circBRD1, circPRDM2, circPTPRS, and circDENND4C). These circRNAs may act as competing endogenous RNA (ceRNA) to upregulate APOA1 expression by absorbing novel_miR_589, thereby regulating angiogenesis and affecting hypoxia adaptation in chicken embryos. The regulatory circRNAs/novel_miR_589/APOA1 axis provides valuable evidence for a better understanding of the specific functions and molecular mechanisms of circRNAs in plateau hypoxia adaptation in Tibetan chickens.
Does prior exposure to larvicides influence dengue virus susceptibility in Aedes aegypti (Diptera: Culicidae)?
Authors: Aldridge Robert L , Alto Barry W , Roxanne Connelly C , Okech Bernard , Siegfried Blair , Eastmond Bradley H , Alomar Abdullah A , Linthicum Kenneth J
Published: October 2023

Control of mosquito vector populations is primarily intended to reduce the transmission of pathogens they transmit. Use of chemical controls, such as larvicides, can have unforeseen consequences on adult traits if not applied properly. The consequences of under application of larvicides are little studied, specifically the impacts on pathogen infection and transmission by the vectors that survive exposure to larvicides. We compared vector susceptibility of Aedes aegypti (L.) for dengue virus, serotype 1 (DENV-1) previously exposed as larvae to an LC50 of different classes of insecticides as formulated larvicides. Larval exposure to insect growth regulators (methoprene and pyriproxyfen) significantly increased susceptibility to infection of DENV-1 in Ae. aegypti adults but did not alter disseminated infection or transmission. Larval exposure to temephos, spinosad, and Bti did not increase infection, disseminated infection, or transmission of DENV-1. Our findings describe a previously under observed phenomenon, the latent effects of select larvicides on mosquito vector susceptibility for arboviruses. These data suggest that there are unintended consequences of sublethal exposure to select larvicides that can influence susceptibility of Ae. aegypti to DENV infection, and indicates the need for further investigation of sublethal effects of insecticides on other aspects of mosquito biology, especially those parameters relevant to a mosquitoes ability to transmit arboviruses (life span, biting behavior, extrinsic incubation period).
Necrophagous insect species succession on decomposed pig carcasses in North Dakota, USA
Authors: Iancu Lavinia , Sahlean Tiberiu , Davis Teya , Simmons Rebecca
Published: October 2023

Necrophagous insect species are widely used during death investigations primarily for the estimation of the minimum postmortem interval, since these species use decomposing organic matter for feeding, oviposition, and larval development. The development stages and successional colonization patterns provide important information for shorter or longer postmortem time intervals. Diptera species are the predominant taxa recovered from decomposed bodies. The temperature variance/seasonality is the main factor affecting the time presence and activity of these species. Other factors, such as geographical location, antemortem conditions, and cause of death, can influence the presence and succession of necrophagous entomofauna. Consequently, successional studies and information regarding species colonization patterns are needed for each geographical region to be used as reference data during death investigations. This study addressed the need to collect forensic entomological data for the State of North Dakota, within the first necrophagous entomofauna diversity report for the month of July 2022, using pig carcasses as human analogs. During the experimental period, 18 species of Diptera and Coleoptera were identified, with 10 new state records, while Calliphoridae was found to be the predominant family. The resulted data on necrophagous insect species diversity and dynamics from exposed pig carcasses will strengthen the current knowledge on forensic entomology in North Dakota and will serve as reference data to be used during death investigations in the Great Plains region.
Radiation-induced gastric injury during radiotherapy: molecular mechanisms and clinical treatment
Authors: Chen Guangxia , Yu Zuxiang , Zhang Yuehua , Liu Shiyu , Chen Chong , Zhang Shuyu
Published: October 2023

Radiotherapy (RT) has been the standard of care for treating a multitude of cancer types. Radiation-induced gastric injury (RIGI) is a common complication of RT for thoracic and abdominal tumors. It manifests acutely as radiation gastritis or gastric ulcers, and chronically as chronic atrophic gastritis or intestinal metaplasia. In recent years, studies have shown that intracellular signals such as oxidative stress response, p38/MAPK pathway and transforming growth factor-β signaling pathway are involved in the progression of RIGI. This review also summarized the risk factors, diagnosis and treatment of this disease. However, the root of therapeutic challenges lies in the incomplete understanding of the mechanisms. Here, we also highlight the potential mechanistic, diagnostic and therapeutic directions of RIGI.
Herpes Simplex Virus Hepatitis in Patients Requiring Intensive Care Unit Admission: A Retrospective, Multicenter, Observational Study
Authors: Frapard Thomas , Amaddeo Giuliana , Decavele Maxens , Abback Paer-Selim , Gaillet Antoine , Bouzbib Charlotte , Vanlemmens Claire , Younan Romy , Canet Emmanuel , Moreau Anne Sophie , Neuville Mathilde , Azoulay Elie , Sitbon Alexandre , Mokart Djamel , Radenne Sylvie , Abergel Armand , Guichon Céline , Roux Olivier , Bonadona Agnes , Mekontso Dessap Armand , De Jong Audrey , Dumortier Jerome , de Prost Nicolas ,   for the GrrrOH and Gref2 study groups, VOIRIOT Guillaume , SCHMIDT Julien , QUENOT Jean Pierre , DECAVELE Maxens , AUDIBERT uliette , CANET Emmanuel , UHEL Fabrice , LESIEUR Olivier , YOUNAN Romy , MOREAU Anne Sophie , DE JOND Audrey , MOKART Djamel , NEUVILLE Mathilde , AZOULAY Elie , AMADDEO Giuliana , ABBACK Paer-Selim , BOUZBIB Charlotte , VANLEMMENS Claire , DUMORTIER Jerome , RADENNE Sylvie , ABERGEL Armand , GUICHON Céline , ROUX Olivier , BONADONA Agnes , CARBONELL Nicolas , SILVAIN Christine , MONTIALOUX Helene , URSIC Jose
Published: October 2023

The clinical features and short-term prognosis of patients admitted to the intensive care unit for herpes hepatitis are lacking. Of 33 patients admitted between 2006 and 2022, 22 were immunocompromised, 4 were pregnant women, and 23 died. Sixteen patients developed a hemophagocytic syndrome. Acyclovir was initiated a median (interquartile range) of 1 (0–3) day after admission.