Stress Patterns Research Articles

Circadian rhythms of antioxidant enzymes activity, clock, and inflammation factors are disrupted in the prefrontal cortex of aged rats. Potential targets for therapeutic strategies for a healthy aging.

Age impairs cognitive functions and antioxidant defenses, for example, by increasing oxidative stress and inflammation in the brain. However, so far, there is no report on the consequences of aging on temporal patterns of proteins and lipids oxidation, antioxidant enzymes activity, endogenous clock and proinflammatory cytokine, in the prefrontal cortex (PFC). Therefore, our objectives here were: 1) to investigate the endogenous nature of 24h-rhythms of lipoperoxidation, protein carbonyls levels, CAT and GPx activity, RORa, and TNFα, in the rat PFC, and 2) to study the consequences of aging on the circadian organization of those factors in the same brain area. To do that, 3- and 22-mo-old male Holtzman rats were maintained under constant darkness conditions during 15 days before reaching the corresponding age. PFC samples were isolated every 4 h, under dim-red light, during a 24h period. Our results revealed circadian patterns of antioxidant enzymes activity, oxidative stress, RORa and TNFα proteins levels, in the PFC of young rats. The circadian distribution of the rhythms’ phases suggests the existence of a reciprocal communication among the antioxidant defenses, the endogenous clock, and the inflammation, in the PFC. Noteworthy, such circadian organization disappears in the PFC of aged rats. An increased oxidative stress would make the redox environment to change into an oxidative status, which alters the endogenous clock activity and disrupts the circadian organization of, at least part, of the antioxidant defenses and the TNFα, in the PFC. These results might highlight novel chronobiological targets for the design of therapeutic strategies addressed to a healthy aging.

Comparison between rupture parameters of intermediate and deep earthquakes at the Peru–Brazil–Bolivia border and northern Chile

We determined the main parameters of the source rupture process of intermediate- and deep-depth earthquakes occurring in the Peru–Brazil–Bolivia border region and northern Chile. The parameters of depth, fault-plane orientation, scalar seismic moment, slip distribution, and radiated seismic energy are obtained from seismograms. We selected 15 intermediate-depth earthquakes (100 km < h < 300 km) and 10 very deep earthquakes (h > 500 km) with magnitudes MW ≥ 6.0. For most events, the slip distribution over the rupture plane shows a single asperity, and the source time function presents a simple pulse. There are differences between intermediate-depth and deep earthquakes. The rupture areas, maximum slip and source time function (STF) duration are larger for intermediate-depth events than for deep events. Additionally, the STF’s show a sharper increase for deep earthquakes. The scaled radiated seismic energy shows larger values for deep depth events. The stress regime pattern derived from the obtained focal mechanism agrees with the geometry of the subduction of the Nazca plate. At intermediate depths, in the northern area up to 12°S, the stress pattern corresponds to a horizontal extension, while in the southern area, the tension axes dip at an angle of 30°. At deep depths, the stress regime corresponds to vertical compression in the north and dips of approximately 45° in the south.

The double pandemic: Examining cultural stress among Asian Americans during the COVID-19 pandemic.

To investigate patterns of cultural stress (racial discrimination and COVID stress) and their impact on ethnic identity and civic engagement among Asian American college students. 491 undergraduate students who self-identify as Asian American (female = 63.50%; Mage = 20.40, SD = 3.64) were recruited from seven college campuses. We identified four distinct cultural stress profiles: COVID-related stress, discrimination stress, double pandemic stress (high in both), and low combined COVID-discrimination stress. Double pandemic profile members were more likely to be immigrants and reported higher ethnic identity, civic behaviors, and belief in civic participation, whereas low combined COVID-discrimination stress participants reported significantly lower beliefs in civic participation compared to those in the double pandemic profile. Findings reaffirm the need to focus on Asian Americans' experiences and expand current conceptualizations of cultural stress to include macrolevel structural processes (COVID stress and racial discrimination) and its implications for identity and civic engagement. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Effect of forefoot transverse arch stiffness on foot biomechanical response--based on finite element method.

The plantar vault, comprising the transverse and longitudinal arches of the human foot, is essential for impact absorption, elastic energy storage, and propulsion. Recent research underscores the importance of the transverse arch, contributing over 40% to midfoot stiffness. This study aimed to quantify biomechanical responses in the ankle-foot complex by varying the stiffness of the deep metatarsal transverse ligament (DTML). Using CT image reconstruction, we constructed a complex three-dimensional finite element model of the foot and ankle joint complex, accounting for geometric complexity and nonlinear characteristics. The focus of our study was to evaluate the effect of different forefoot transverse arch stiffness, that is, different Young's modulus values of DTML (from 135MPa to 405MPa), on different biomechanical aspects of the foot and ankle complex. Notably, we analyzed their effects on plantar pressure distribution, metatarsal stress patterns, navicular subsidence, and plantar fascial strain. Increasing the stiffness of the DTML has significant effects on foot biomechanics. Specifically, higher DTML stiffness leads to elevate von Mises stress in the 1st, 2nd, and 3rd metatarsals, while concurrently reducing plantar pressure by 14.2% when the Young's modulus is doubled. This stiffening also impedes navicular bone subsidence and foot lengthening. Notably, a 100% increase in the Young's modulus of DTML results in a 54.1% decrease in scaphoid subsidence and a 2.5% decrease in foot lengthening, which collectively contribute to a 33.1% enhancement in foot longitudinal stiffness. Additionally, doubling the Young's modulus of DTML can reduce the strain stretch of the plantar fascia by 38.5%. Preserving DTML integrity sustains the transverse arch, enhancing foot longitudinal stiffness and elastic responsiveness. These findings have implications for treating arch dysfunction and provide insights for shoe developers seeking to enhance propulsion.

Decoding Cancer Risk: Understanding Gene-Environment Interactions in Cancer Development.

While lifestyle choices or behavioral patterns remain the most significant factors influencing cancer risk, environmental exposure to certain chemicals, both manufactured and natural, may also contribute to an individual's likelihood of developing cancer. This interplay of factors, coupled with an aging demographic and shifting lifestyle patterns, has led to an increasing prevalence of cancer in recent years. This study examines the environmental and behavioral factors that contribute to anomalies in the immune system and increase the riskof developing cancer. Significant environmental and occupational factorsinclude the contamination of air and water, exposure to radiation, contact with harmful microorganisms and pathogens, and workplace exposure to carcinogens such as asbestos, certain chemicals, and industrial pollutants. Behavioral factors, such as food, physical activity, stress, substance misuse, and sleep patterns, have a substantial impact on immunological function and the likelihood of developing cancer. For example, pollutants like benzene and arsenic can disrupt immune function and raise the risk of developing cancer. Similarly, lifestyle variables such as inactivity and poor nutrition have been linked to an increased risk of cancer. Long-term stress and substance abuse can also decrease immunological responses, increasing the risk of developing cancer. The review underlines the complexities of examining gene-environment interactions, as well as the importance of using several perspectives to fully comprehend these pathways. Future investigations should emphasize improved methodology and larger sample sizes. Public health campaigns should aim to reduce human exposure to cancer-causing compounds known as carcinogens while also encouraging the adoption of healthy behaviors and habits. Tailored preventive approaches that account for individual genetic vulnerabilities have the potential to improve cancer prevention and treatment.

Structural behavior and mechanical fatigue of plate and shell heat exchangers through finite element analysis

Plate and Shell Heat Exchangers (PSHE) are vital in industries due to their adaptability and efficiency. This study applied the finite element method to analyze PSHE plate behavior, which is challenging to assess experimentally. The equivalent von Mises stress field was determined for four-plate setups under different conditions: internal channel pressure, external channel pressure, and pressure in both branches. Peak stresses were found at corrugation tops during contact, varying stress levels based on operating conditions. Stresses decreased when both branches were pressurized but increased with single-branch pressurization. Internal and external pressure-only scenarios had distinct stress patterns. The chevron angle and corrugation contact points influenced plate stiffness and stress distribution. A fatigue analysis assessed plate lifespan under cyclic loads, with fatigue strength reduction factors applied according to Soderberg, Goodman, and Gerber failure criteria. This comprehensive analysis provides critical insights into PSHE plate performance, aiding in their reliable application in the industry. All numerical data obtained in this work were validated based on experimental studies previously published in the literature for stress and fatigue analysis.

Experimental Study on Key Techniques for the Construction of High Asphalt Concrete Core Rockfill Dam under Unfavorable Geological Conditions

Asphalt concrete core dams (ACCDs) have been widely constructed in Xinjiang, yet the design of materials and structures has mainly relied on empirical knowledge without substantial theoretical grounding. In this study, we carried out a large-scale relative density test of gravel material in Bamudun dam, studied the compaction characteristics of gravel material, and determined the relative density characteristic index, in order to provide a basis for the subsequent dam material rolling test and construction quality inspection. Furthermore, in order to improve the efficiency of dam construction in narrow valleys, we optimized the connection type between asphalt concrete core wall and bedrock, and proposed a rapid construction method of paving core wall after pouring mass concrete base on bedrock. Finally, we established a three-dimensional finite element model to systematically analyze the stress and deformation patterns of the dam body, core wall, and base of the ACCD at Bamudun. The results show that the maximum compressive stress suffered by the core wall during the full storage period is 1.62 MPa, there is no tensile stress, and the risk of hydraulic splitting is small. The stress and deformation levels of each part are within the safe range. This verifies the rationality of the rapid construction method. The research findings can provide a great theoretical significance and engineering value for the safe design and construction of ACCDs.

How does virtual water influence the water stress pattern in Africa? A research perspective from the perspectives of production and trade

Northern Africa has become the first region in the world to exhaust its water resources, with a 40 % decrease in per capita water availability south of the Sahara over the past decade. While adjusting production structures and consumption can regulate the supply-demand dynamics of water resources, the extent of the impact of virtual water-induced pressure on both the regional and national levels in Africa remains largely understudied. Applying the standard Penman formula, this research calculates the water footprint of eight cereal crops in 54 African countries from 1990 to 2021. By integrating corresponding data on cereal trade, the study analyzes changes in virtual water stress. The findings indicate a decline in the per-unit production and consumption water footprints for African cereals. However, the continuous expansion of cultivation areas contributes to a rising water stress. In comparison to 1990, the water stress for soybeans, sorghum, rice, maize, and cassava increased by 149.72 %, 146.88 %, 133.89 %, 123.30 %, and 90.8 %, respectively, in 2021. Only barley showed a reduction in water stress by 23.22 %. The study underscores the growing interconnectedness of virtual water trade (VWT) among African nations from 1990 to 2021, leading to a more balanced trade distribution. VWT has reduced water stress by 7.65 %, 2.08 %, and 1.8 % in Western, Central, and Northern Africa, respectively, while increasing pressure in Southern and Eastern Africa by 10.51 % and 1.01 %. The flow of virtual water in Africa is most influenced by spatial proximity, primarily occurring between adjacent countries or regions. Forecasts for water stress under the five scenarios of SSPs-RCP8.5 have been conducted, revealing a continuous increase in water stress across Africa. Furthermore, analysis of the SSP2-RCP8.5 scenario indicates that by 2030 and 2040, African cereal crops are projected to face virtual water resource stress increases of 7 % and 18.76 %, respectively, compared to 2020 levels. During the same period, Sierra Leone is anticipated to experience a growth rate in virtual water stress of approximately 1903.38 %. Consequently, altering crop cultivation structures and enhancing VWT are poised to alleviate water resource pressure, promoting the scientific management of agricultural water resources in Africa.

Comparative Study of Shatpuspa Tail Matra Basti with Dasmool Tail Matra Basti in Anartav W.S.R. to Vata Kaphaj Aartav Dusti (PCOS)

Women’s health is always being prime concern for medical fraternity since female not only serve for her family but also support society and nation. The current scenario witnessed rise in female health issues due to the stressful pattern of life style. Women of reproductive age mainly suffer with many gynecological problems and many of them experience hormonal imbalances which lead to menstrual irregularities. Currently many women are facing issues of polycystic ovarian syndrome (PCOS) globally which also affects physiology of normal menstruation. The incidences of PCOS are very high now a days due to the poor daily routines and sedentary lifestyles, etc. In Ayurveda menstrual abnormalities associated with PCOS can be correlated with Anartav caused by Vata Kaphaj Aartav Dusti. Ayurveda suggested many therapeutic options for such conditions including Basti therapy especially Matra Basti. Considering these facts present article reviewed role of Shatpuspa Tail Matra Basti and Dasmool Tail Matra Basti in Anartav W.S.R. to Vata Kaphaj Aartav Dusti (PCOS).

Probing the Thermal Stability and Microstructural-Mechanical Behaviour of Laser-Welded 17-4 PH Stainless Steel

Dissimilar-weld-fabrications are created to capture privilege of certain attributes of each component to enhance the potential of overall structure. Induced residual stress owing to non-uniform thermal cycle, strain developed by virtue of metallurgicaltransformation, and dramatic difference in thermo-physical and thermo-mechanical property, proved to be a major drawback and limits application certainly. Present study includes amalgamation of material-characterization and numerical-modelling to overcome aforementioned issue. The 17-4 precipitation-hardened steel was joined with SS316 steel by CO2 laser-welding technique using different-heat-input. It is noticed that the distribution and amount of δ-ferrite controls the on-site behavior relating to thermal stability, microstructural characteristics and residual stress generation. This work is attempted to understand thermal behavior as well as its correlation with δ-ferrite formation and residual stress distribution. Sequential-coupled-thermo-mechanical model proposed to developed for dissimilar weld joints at different process conditions. Finally, the interrelation between microstructure and the typical pattern of residual stress believed to be investigated systematically.

A Comparative Evaluation of Stress Distribution Around Different Widths of Implant and Bony Interface in Function During Axial and Non-axial Loading: A Finite Element Analysis.

The study employed three-dimensional (3D) finite element analysis (FEA) and examined how implant diameters affect stress distribution across the implant-bone contact and how stress transmission through this interface changes during axial and non-axial loading. A 3D mandibular model was created using cone beam CT of a patient with implants inserted into the first mandible molar. Nobel Biocare implants (Nobel Biocare, Switzerland) with specific dimensions of 3.5 mm, 4.3 mm, 5.0 mm, and 6.0 mm were chosen. Models were created in CATIAV5R19 (Dassault Systemes, France) from threaded titanium implant dimensions. Implants were finite element-modeled utilizing ANSYS Workbench v11.0 (Ansys, Inc, Pennsylvania, USA). The analysis involved applying 100 N axial, 50 N buccolingual, and 50 N mesiodistal loads. In a lower first molar bone segment, the implant top surface was loaded in 100 N axial, 50 N buccolingual, and 50 N mesiodistal orientations. The cortical bone proximal to the implant neck had the most von Mises stress, regardless of model or stress scenario. In Model I cortical bone, maximal stress was centered at the implant neck. Most stress was on lingual bone plates, lesser on buccal, and least on mesial and distal. Less than half of the implant stress was transmitted to the cortical bone. The stress transferred from the implant to the cortical bone in Model II was less than half of the implant stress. The same was true for Models III and IV. In Model I cancellous bone, stress was concentrated in the implant's coronal half and minimal in the apical half. The stress patterns under axial loading were distributed favorably. Therefore, it can be inferred that an augmentation in the diameter of the implant enhances the even distribution of stress at the interface between the bone and the implant by offering a larger surface area for the dispersion of stress. Furthermore, it was determined that applying force along an implant's axis was a beneficial loading direction and did not negatively impact its lifespan.

Identification of oxidative stress signatures of lung adenocarcinoma and prediction of patient prognosis or treatment response with single-cell RNA sequencing and bulk RNA sequencing data

Lung adenocarcinoma (LUAD), the most common subtype of lung cancer globally, has seen improved prognosis with advancements in diagnostic, surgical, radiotherapy, and molecular therapy techniques, while its 5-year survival rate remains low. Molecular biomarkers provide prognostic value. Oxidative stress factors, such as reactive nitrogen species and ROS, are crucial in various stages of tumor progression, influencing cell transformation, proliferation, angiogenesis, and metastasis. ROS demonstrate dual roles, affecting tumor cells, hypoxia sensitivity, and the microenvironment. Comprehensive analysis of oxidative stress in LUAD has not been conducted to date. Therefore, we systematically investigated the regulatory patterns of oxidative stress in LUAD based on oxidative stress-related genes and correlated these patterns with cellular infiltration characteristics of the tumor immune microenvironment. The model utilizes single-factor Cox analysis to screen key differential genes with prognostic value and employs least absolute shrinkage and selection operator (LASSO) penalized Cox regression analysis to construct a prognostic-related prediction model. Ten candidate genes were selected based on this model. The risk score was constructed using the coefficients and expression levels of these ten genes. Furthermore, the impact of this risk score on overall survival (OS) was determined. Two genes with the most significant differential expression, SFTPB and S100P, were selected through qRT-PCR. Cell experiments including CCK-8, Edu, transwell assays confirmed their effects on lung cancer cells growth, consistent with the results of bioinformatics analysis. These findings suggested that this model held potential clinical value for evaluating the prognosis of lung adenocarcinoma.

Designing Novel Endodontic Implants and Evaluation of the Stress Distribution in Maxillary Anteriors Using Finite Element Analysis.

Introduction Endodontic implants, or didontic implants, offer a promising solution for stabilizing compromised teeth with a guarded prognosis and prolonging their clinical survival rate. Despite their potential benefits, they retired out of practice due to failures that arose from the lack of a biocompatible seal and engaging in dentin. Novel designs, based on evidence-based research with the help of bioceramics, present an opportunity to overcome these challenges andhence, enhance the clinical efficacy of endodontic implants. Thus the aim of this study is to design novel endodontic implants and evaluate their stress distribution in maxillary incisors using finite element analysis (FEA). Materials and methodology FEAis a biomechanical study to assess the stress distribution and extent of displacementto assess the clinical efficacy of novel endodontic implants in maxillary anterior teeth. Three 3D models (Model 1, Model 2, and Model 3)are designed to be meshed, and material elastic properties of the tooth and periapical tissues are applied. Boundary conditions were established, and a constant axial load value of 600 N was applied at a 45° angle. The FEA analysis was done under the loading conditions to assess the stress patterns for the three 3D models in comparison to the intact tooth on the ANSYS software (ANSYS Inc, Pennsylvania). Results FEA simulations revealed the distribution of stress within the tooth structure under functional occlusal forces, as Von Misses stresses were analyzed to assess the likelihood of material yielding and failure, which was comparable to that of an intact tooth. The maximum stress of deformation was as follows: intact: 1.7589e-5 MAX; Model 1:3.3804e-6 MAX; Model 2:2.638e-5 MAX; and Model 3: 2.1986e-5 MAX. The area of stress concentrations did not occur at the interface of the coronal or apical seal, which prevented catastrophic failures. Conclusion By leveraging advanced design principles and materials, these implants offer a promising alternative to traditional approaches,particularlyin trauma cases with a poor prognosis for the survival of the teeth leading to loss of tooth. Further clinical studies are warranted to validate the efficacy and long-term success of these novel endodontic implants in diverse patient populations.

The Stiffness of the Ascending Aorta Has a Direct Impact on Left Ventricular Function: An In Silico Model.

During systole, longitudinal shortening of the left ventricle (LV) displaces the aortic root toward the apex of the heart and stretches the ascending aorta (AA). An in silico study (Living Left Heart Human Model, Dassault Systèmes Simulia Corporation) demonstrated that stiffening of the AA affects myocardial stress and LV strain patterns. With AA stiffening, myofiber stress increased overall in the LV, with particularly high-stress areas at the septum. The most pronounced reduction in strain was noted along the septal longitudinal region. The pressure-volume loops showed that AA stiffening caused a deterioration in LV function, with increased end-systolic volume, reduced systolic LV pressure, decreased stroke volume and effective stroke work, but elevated end-diastolic pressure. An increase in myofiber contractility indicated that stroke volume and effective stroke work could be recovered, with an increase in LV end-systolic pressure and a decrease in end-diastolic pressure. Longitudinal and radial strains remained reduced, but circumferential strains increased over baseline, compensating for lost longitudinal LV function. Myofiber stress increased overall, with the most dramatic increase in the septal region and the LV apex. We demonstrate a direct mechanical pathophysiologic link between stiff AA and reduced longitudinal left ventricular strain which are common in patients with HFpEF.

Model‐based multi‐genotype characterization of drought stress Target Population of Environments for the common bean in East Africa

AbstractEfforts toward the development of common bean varieties that can perform better under the drought conditions in Eastern Africa are constrained by significant genotype–environment–management (G × E × M) interactions. To address this, an attempt was made previously to assess drought stress for Eastern Africa using the Target Population of Environments (TPE) approach, albeit by using a single cultivar. Here, we extend earlier TPE work with a larger sample of representative genotypes from East Africa including commercial and breeding lines. By using a larger genotype pool, we are able to (1) assess the extent to which TPEs identified vary across genotypes (i.e., generality of the TPEs) and (2) identify best‐performing genotypes for the various environments identified. To perform the analyses, we used the CROPGRO‐DRYBEAN cropping system model available in the Decision Support System for Agrotechnology Transfer (DSSAT) v4.7 calibrated and evaluated from field trials in Africa and Colombia with 10 genotypes. Our findings indicate that despite some level of genotype‐related variation, the dominant drought stress patterns, and their priorities—drought stress‐free conditions remain the dominant TPE, followed by terminal drought stress—remain unaltered. Moreover, we find that it is possible to reduce the extent and intensity of drought stress in various TPEs by adequately targeting genotypes from the pool considered herein. Importantly, the genotype characteristics for stress‐free, extreme terminal drought and moderate terminal drought stress are significantly different, confirming a differentiated breeding strategy is required between the TPEs. The findings from this study are useful for the modernization of the bean breeding programs in Africa.

The use of Cauchy-type singular integrals over neighboring intervals to compute induced slip in displaced faults

We present expressions to compute the inverse of a Cauchy-type singular integral equation representing the relation between a double-peaked Coulomb stress in a fault or fracture and the resulting slip gradient in two distinct collinear slip patches. In particular we consider a situation where the patches are close enough to account for the influence of the slip gradient in one patch on the slip-induced shear stress in the other patch and vice versa. This situation can occur during depletion-induced or injection-induced fault slip in subsurface reservoirs for, e.g., natural gas production, hydrogen or CO2 storage, or geothermal operations. The theory for a single slip patch is well-developed but the situation is less clear for a configuration with two patches although the monographs of Muskhelishvili (1953) and Weertman (1996) provide earlier results. We show that the general inverse solution for the coupled two-patch problem requires six auxiliary conditions to ensure six physical requirements: boundedness of the slip gradient at the four end points of the slip patches and vanishing of the integrals of the slip gradient over the patches. Mathematically, the presence of two additional conditions, as compared to earlier formulations, corresponds to two undetermined coefficients in the general solution of the governing integral equation. Numerical simulation confirms that at least one of these is always non-zero in the coupled situation. For a coupled double-patch case with a symmetric pre-slip Coulomb stress pattern, the general inverse solution requires three auxiliary conditions. Moreover the conditions for the asymmetric case may be reduced to a set of four again, but these are different from the sets of four obtained earlier by Muskhelishvili (1953) and Weertman (1996). We illustrate the theory with a numerical example in which the evaluation of the Cauchy integrals is performed with a modified version of augmented Gauss–Chebyshev quadrature that relies on analytical inversion.

Stress-related transcriptomic changes associated with GFP transgene expression and active transgene silencing in plants

Plants respond to biotic and abiotic stress by activating and interacting with multiple defense pathways, allowing for an efficient global defense response. RNA silencing is a conserved mechanism of regulation of gene expression directed by small RNAs important in acquired plant immunity and especially virus and transgene repression. Several RNA silencing pathways in plants are crucial to control developmental processes and provide protection against abiotic and biotic stresses as well as invasive nucleic acids such as viruses and transposable elements. Various notable studies have shed light on the genes, small RNAs, and mechanisms involved in plant RNA silencing. However, published research on the potential interactions between RNA silencing and other plant stress responses is limited. In the present study, we tested the hypothesis that spreading and maintenance of systemic post-transcriptional gene silencing (PTGS) of a GFP transgene are associated with transcriptional changes that pertain to non-RNA silencing-based stress responses. To this end, we analyzed the structure and function of the photosynthetic apparatus and conducted whole transcriptome analysis in a transgenic line of Nicotiana benthamiana that spontaneously initiates transgene silencing, at different stages of systemic GFP-PTGS. In vivo analysis of chlorophyll a fluorescence yield and expression levels of key photosynthetic genes indicates that photosynthetic activity remains unaffected by systemic GFP-PTGS. However, transcriptomic analysis reveals that spreading and maintenance of GFP-PTGS are associated with transcriptional reprogramming of genes that are involved in abiotic stress responses and pattern- or effector-triggered immunity-based stress responses. These findings suggest that systemic PTGS may affect non-RNA-silencing-based defense pathways in N. benthamiana, providing new insights into the complex interplay between different plant stress responses.

Machine learning in prediction of residual stress in laser shock peening for maximizing residual compressive stress formation

Laser Shock Peening (LSP) is an advanced technique for enhancing surface properties, drawing significant interest for its ability to induce beneficial residual stresses in materials. Traditional LSP design processes, reliant on manual parameter selection, often result in imprecise control over the stress distribution, necessitating multiple iterations and high costs. This study introduces a machine learning (ML)-based approach, utilizing the Random Forest (RF) algorithm, to automate and optimize the design of LSP parameters for nickel-aluminium bronze surfaces. Our findings demonstrate the RF model’s capability to accurately predict and optimize residual stress distributions, achieving compressive stresses up to 472 MPa with a notable reduction in design iterations. The model forecasts both uniform and non-uniform stress patterns, particularly identifying areas susceptible to Residual Stress Holes (RSH) with improved precision. With an Absolute Percentage Error (APE) of only 6.2 %, our approach significantly outperforms traditional ML algorithms, offering a novel method for efficiently designing complex residual stress fields in LSP applications.

Comparative analysis of geometric imperfections and residual stresses on the global stability behavior of cantilever composite alveolar beams

Few studies addressed the influence of geometric and structural imperfections of steel alveolar I-sections on the stability behavior of composite beams under hogging moment. Therefore, this paper aims to study the sensitivity to geometric imperfection amplitude and residual stress distribution on their global stability. The research primarily focuses on comparing numerical results with experimental data in detail, which addresses four tests involving cantilever composite beams with castellated and cellular I-sections. It includes applying various residual stress patterns and geometric imperfection values to advanced numerical analyses as documented in the literature. Linear buckling analyses (LBA) and geometrically and materially nonlinear analyses with imperfections (GMNIA) are carried out using the ABAQUS software. Regarding the first positive eigenvalue from LBA analyses, the eigenvectors presented Web-Post Buckling (WPB) with a slight compressed flange lateral curvature, inserted as the initial geometric imperfection in the GMNIA analyses. However, when the residual stresses were implemented in the GMNIA analyses, some finite element models had different failure modes regarding the deformed configurations from LBA analyses, in which the failure modes were characterized by Lateral-Distortional Buckling (LDB), which was in agreement with the test results. As the beams reached LDB in an inelastic regime, residual stresses significantly affected their resistant capacity. This way, the distribution of compressive residual stresses in the flanges had the most critical influence on the global stability behavior of the analyzed beams, as these residual stresses favor the LDB occurrence. Finally, higher geometric imperfection amplitudes did not provide only lower ultimate loads, as when the instability phenomena are reached in an inelastic regime, the effect of global geometric imperfections becomes highly complex.

The Role of Prosody and Intonation in English Phonology: Implications for Speech Perception and Production

The role of prosody and intonation in English phonology has significant implications for speech perception and production. These phonological processes influence how words are understood and articulated in English. Recent studies have shown that prosody and intonation play a crucial role in verbal communication. This article aims to investigate the importance of prosody and intonation in understanding and producing speech in English language learning intonation refers to the melodic pattern in speech that can change the meaning of a sentence. It is often used to convey emotions or to emphasize a message. On the other hand, prosody encompasses the patterns of pitch, stress, and duration in speech that impact word articulation and comprehension. Both work together to create accurate articulation and understanding of words in English this linguistic study underscores the importance of prosody and intonation in English language learning and elucidates how these two aspects influence speech perception and production. With a deep understanding of prosody and intonation, learners can enhance their ability to communicate in English more effectively and accurately.