Stress Patterns Research Articles

Trajectories of maternal parenting stress and adolescent behavioral symptoms in unmarried families: The role of family immigration status

BackgroundMaternal parenting stress during childhood may have important influences on offspring internalizing and externalizing behaviors during adolescence in unmarried households, but it is unclear whether effects differ across different trajectory patterns of maternal parenting stress and for native-born vs. immigrant families. MethodsUsing data from the Future of Families and Child Wellbeing Study, we identified trajectory patterns of maternal parenting stress from ages 1–9 years using semi-parametric group-based trajectory modeling. We used negative binomial regression models to estimate associations between maternal parenting stress trajectories and adolescent behavioral symptoms at age fifteen. ResultsFive maternal parenting stress trajectory groups were identified among the 1982 unmarried families included in this study, representing consistently low (9.2 %), consistently mild (54.2 %), moderate and decreasing (14.4 %), moderate and increasing (16.0 %) and consistently high (6.2 %) levels of maternal parenting stress. For adolescent internalizing symptoms, all maternal parenting stress trajectory groups exhibited higher symptoms compared to the consistently low group: IRR for consistently mild: 1.21 (95 % CI: 0.98–1.56); IRR for moderate/decreasing: 1.34 (95 % CI: 1.04–1.74); IRR for moderate/increasing: 1.62 (95 % CI: 1.28–2.13); and IRR for consistently high: 1.74 (95 % CI = 1.29–2.41). Similar results were observed for adolescent externalizing symptoms. Stronger effects of maternal parenting stress trajectories on adolescent externalizing symptoms were observed among native-born vs. immigrant families. LimitationsDifferential attrition and same-source bias may lead to under- or over-estimation of the associations of interest. ConclusionsInterventions targeting unmarried families with elevated maternal parenting stress during childhood may reduce behavioral symptoms in adolescence.

Evaluating the Feasibility of Short Dental Implants as Alternatives to Long Dental Implants in Mandibular Bone: A Finite Element Study.

This study uses finite element analysis to investigate the potential application of shorter dental implants as a substitute for longer implants in the lower jaw (mandible). FEA allows the evaluation of the stress patterns around the implant-bone interface, a critical factor for successful osseointegration. Ten models were generated, encompassing five long (L1-L5) and five short implant models (S1-S5) with variations in diameter and length. Hypermesh software was utilized to meticulously prepare the FEA models, ensuring accurate mesh generation. The FEA simulations were conducted under four distinct loading scenarios (100 N occlusal load, 40 N lateral load, 100 N oblique at 30°, and 100 N oblique at 45°) to realistically mimic the forces exerted during biting, using an ABAQUS CAE solver. The results revealed that the von Mises stress generated within the short implant models was demonstrably lower compared to their long implants. Additionally, a significant drop in stress was observed with increasing the diameter of the short implants, to a certain diameter range. These findings suggest the potential for successful substitution of long implant model L4 with short implant model S4 due to the demonstrably lower stress values achieved. Furthermore, the data indicates the possibility of utilizing short implant models S3 and S5 as alternatives to long implant models L3 and L5, respectively. These observations hold significant promise for evaluating the feasibility of replacing long implants with shorter variants, potentially leading to a reduction in implant-related failures.

A framework for evaluating the combined effects of water transfer and storage strategies on water stress alleviation

Water transfer and storage are two effective anthropogenic management strategies to alleviate the contradictions between water supply and demand. However, the trade-off and synergistic impacts of management strategies in alleviating water stress remain unclear at the national level. Therefore, this study proposes a framework that integrates the fraction of runoff being withdrawn (scarcity coefficient) and the variation of runoff weighted by reservoir (variability coefficient) to evaluate the multifaceted impacts of management strategies on water stress mitigation. The proposed framework evaluates the changes in both the water supply–demand balance and the historical variability of runoff by considering physical water transfers, virtual water flows, and reservoir operations. This study applied the framework to evaluate the spatiotemporal patterns of water stress and used principal component analysis to estimate the relative contributions of management strategies across ten first-order basins in China for the period of 2014–2018. Results show that water-resource scarcity coefficient varied between −37.15% and 13.28% at the basin scale (the national average varied −5%) and water-resource variability coefficient varied between −100% and −19.26% at the basin scale (the national average varied −61.11%). Management strategies, incorporating water transfer and storage strategies, shifted the distribution patterns of national water stress. The attribution analysis revealed that reservoir storage capacity was the largest contributor to the first principal component representing infrastructure element, whereas the second component representing economic element was affected by the net virtual water inflows. Overall, through exploring the outcomes of combined effects among management strategies, this proposed framework provides a comprehensive perspective for investigating how human activity alleviates regional water stress.

Research on the Application of Cushion and Isolation Materials in Protecting the over Shield Tunnel

The portal frame, as an innovative subway protection structure, primarily serves the development of underground spaces above shield tunneling for subways. It comprises foundation piles along both sides of the tunnel and a transition thick plate. When the transfer thick plate sustains loads at its midspan, deformation occurs, interacting with the underlying soil to generate additional stresses, thereby potentially impacting the subway tunnel beneath negatively. This study, anchored in the real-case scenario of Qianhai Exchange Square, employs finite element analysis to investigate the interaction mechanisms between the transfer thick plate under midspan loading and soils of varying properties. Findings revealed a characteristic distribution pattern of additional stresses in the soil—smaller at the edges and larger at the center. Furthermore, under equal loading conditions, there's a positive correlation between soil stiffness and induced additional stress, while an inverse relationship exists with the vertical deformation of the transfer thick plate. In response to this issue, the paper innovatively proposes embedding a cushioning and isolation layer under the transfer thick plate. Based on the results of full-scale tunnel tests carried out during the early stages of the project, and by employing high-precision finite element simulations, the bearing capacity of the tunnel was determined. This analysis, in turn, informed the formulation of selection principles for the cushioning and isolation materials in a feedback manner. Computational verifications showed that appropriately designing the cushioning and isolation layer can significantly reduce additional stresses in the foundation soil, thereby effectively alleviating the impact of concentrated upper loads on the shield tunnel.

Polymer gear failure prediction: A regression-Based approach using FEA and photoelasticity technique

The research aims to develop a model to predict the maximum contact stress depth, which will be correlated with polymer gear failures such as wear and rapid thermal deformation. A thorough 3D Finite Element Analysis (FEA) was performed for different gear parameters (varying module, number of teeth, and face width) in different combinations (Polymer – Polymer, Steel – Polymer, and Polymer – Steel). The simulation results showed that the contact stress depth increases with respect to the module and number of teeth; meanwhile, very negligible variations were found along the face width. Also, the findings indicate that the contact stress depth varied in the following descending combinations of gear pair: Polymer – Polymer, Steel – Polymer, and Polymer – Steel. The 3D FEA contact stress patterns were validated experimentally by utilizing the in-house developed photoelasticity test rig. The data obtained from the simulation results were used to develop regression models (Linear regression and Random Forest regressor) for estimating the maximum contact stress depth. A feature importance study was done using the mean reduction of the Gini index or impurities in random forest. It was found that torque applied and contact width of the gear pair were significantly influenced by the contact stress depth. Finally, an equation was developed correlating torque and contact width to predict the depth occurrence of maximum contact stress through which the failure mode of the polymer gear could be predicted.

Use of tobacco during COVID-19: A qualitative study among medically underserved individuals.

The COVID-19 pandemic produced stress for people around the world. The perception that tobacco can be a coping tool for stress relief suggests that the conditions during the COVID-19 pandemic can provide insight into the relationship between stress and tobacco use patterns, particularly among those most at risk for severe COVID-19 disease. The goal was to identify the impacts of the COVID-19 pandemic on tobacco use and preparedness for smoking cessation among individuals who smoke and are older and medically underserved. We conducted in-depth interviews with 39 patients to learn about individuals' smoking behavior during the COVID-19 pandemic. We used a modified grounded theory approach to code and analyze all qualitative data. We conducted thematic analysis to identify key factors associated with smoking behaviors during COVID-19. Our results indicated that increases in perceived stress and social isolation may have been associated with increased tobacco use during the COVID-19 pandemic. Pandemic-related social isolation contributed to increases in smoking, despite respondents being concerned about the severity of COVID-19. While many respondents felt that smoking relieved their stress from the pandemic, they appeared unaware of the stress-inducing properties of tobacco use. Our findings indicate that pandemic-related stress impacted smoking behavior among older, medically underserved smokers. Results may assist clinicians in addressing the role of tobacco use in response to highly stressful events. Smoking cessation strategies should consider the implications of stress on smoking behavior, including smoking relapse in response to highly stressful events-particularly for medically underserved populations.

Mandibular biomechanics rehabilitated with different prosthetic restorations under normal and impact loading scenarios

BackgroundRestorative treatment options for edentulous patients range from traditional dentures to fixed restorations. The proper selection of materials greatly influences the longevity and stability of fixed restorations. Most prosthetic parts are frequently fabricated from titanium. Ceramics (e.g. zirconia) and polymers (e.g. PEEK and BIOHPP) have recently been included in these fabrications. The mandibular movement produces complex patterns of stress and strain. Mandibular fractures may result from these stresses and strains exceeding the critical limits because of the impact force from falls or accidents. Therefore, it is necessary to evaluate the biomechanical behavior of the edentulous mandible with different restorations under different loading situations.ObjectiveThis study analyzes the biomechanical behavior of mandibles after four prosthetic restorations for rehabilitation under normal and impact loading scenarios.Material and MethodsThe mandibular model was constructed with a fixed restoration, which was simulated using various materials (e.g. Titanium, Zirconia & BIOHPP), under frontal bite force, maximum intercuspation, and chin impact force. From the extraction of tensile and compressive stresses and strains, as well as the total deformation of mandible segments, the biomechanical behavior and clinical situations were studied.ResultsUnder frontal bite, the anterior body exhibited the highest tensile (60.34 MPa) and compressive (108.81 MPa) stresses using restoration 4, while the condyles and angles had the lowest tensile (7.12 MPa) and compressive (12.67 MPa) stresses using restoration 3. Under maximum intercuspation, the highest tensile (40.02 MPa) and compressive (98.87 MPa) stresses were generated on the anterior body of the cortical bone using restoration 4. Additionally, the lowest tensile (7.7 MPa) and compressive (10.08 MPa) stresses were generated on the condyles and angles, respectively, using restoration 3. Under chin impact, the highest tensile (374.57 MPa) and compressive (387.3 MPa) stresses were generated on the anterior body using restoration 4. Additionally, the lowest tensile (0.65 MPa) and compressive (0.57 MPa) stresses were generated on the coronoid processes using restoration 3. For all loading scenarios, the anterior body of the mandible had the highest stress and strain values compared with the other segments. Compared to the traditional titanium restoration.2, restoration.1(zirconia) increases the tensile and compressive stresses and strains on the mandibular segments, in contrast to restoration.3 (BIOHPP). In addition, zirconia implants exhibited higher displacements than the other implants.ConclusionIn the normal loading scenario, the tensile and compressive stresses and strains on the mandible were within the allowable limits when all restorations were used. Under the chin impact loading scenario, the anterior body of the mandible was damaged by restorations 1 and 4.

Research on the Mechanism of Loose Deformation in Weak Fracture Zone Tunnel Surrounding Rock and Support Control

In the fractured weak fault zone, rock mass exhibits low strength and poor self-stability. The geological conditions are complex, and when tunnels cross through fractured zones, significant deformations and collapses are prone to occur, leading to geological hazards. This paper investigates the in situ stress and deformation patterns of the Dongmachang Tunnel No. 1, proposing support solutions for addressing tunnel deformations through field experiments and numerical simulations. The on-site monitoring results indicate that despite implementing measures such as grouting reinforcement and temporary steel supports to control surrounding rock deformation, significant structural damage still occurred in the tunnel support system. The manifestations included severe sinking and cracking of the arch crown, strong inward deformation of the sidewalls, widespread cracking, crushing, and spalling of shotcrete, slight arching uplift, and severe distortion and twisting of steel arches forming a “Z” or “S” shape. To ensure tunnel safety and control the stability of excavations in weak fault zones, a comparison of tunnel deformation support schemes is conducted through field experiments and numerical simulations, indicating that replacing the upper tunnel structure and invert can effectively prevent tunnel deformations. These measures are vital for the sustainable development of tunnel.

Evaluation of Surface Morphology and Stress Distribution of Orthodontic Mini-implants in Maxilla: A Three-dimensional Finite Element Study

Objectives: Inaccurate design, insertion or loading of mini-implant may lead to disturbed bone turnover and subsequent implant failure. This study assesses the two commonly used types of implants and their bone stress pattern and determines which type of implant may be more patient-compatible. Method: The samples were categorized into four groups and analyzed by scanning electron microscopy to assess the surface morphology. Stress distribution was estimated using finite element method for which three-dimensional (3D) models of the maxilla and mini-screws were prepared. The implant was then inserted 5 mm from the alveolar crest onto the buccal cortical plate of maxilla between the second premolar and first molar within the platform of Ansys Workbench software. Two loads were applied: 5 Ncm and 2 N. Evaluation of von Mises stresses in the bone was estimated. Results: The study concluded that tapered stainless steel screws exerted greater stress on the bone than titanium screws in both situations. As the diameter increased from 1.3 mm to 1.5 mm, the mini-screw displacement and stress were less. Under 2 N force, the stress was distributed around the head and neck of the mini-implant and the cortical bone. Conclusion: The assessment of von Mises stress distributed around an orthodontic mini-implant under a constant load revealed that stainless steel mini-screws generated more stress than titanium mini-screws. It was observed that the majority of the stress and strain is tolerated by the cortical bone, not the cancellous bone. The diameter of mini-screw is more significant irrespective of material composition.

Biocompatibility, thermal and mechanical properties of glass fiber‐reinforced polybenzoxazine composites as a potential new endodontic post

AbstractA novel dental fiber post from glass fiber‐reinforced polybenzoxazine (PBZ) composites was developed in this work. The essential properties, that is, chemical characteristics, thermal and biological properties of the PBZ composites were investigated for various glass fiber loadings (10.5, 23.7, 41.2 and 65.1 vol%). Finite element analysis (FEA) was also utilized to observe mechanical behaviors of the tooth model repaired with PBZ composite posts compared to a natural tooth model. The findings reveal that for the fiber‐reinforced PBZ composites not only their thermal properties were significantly improved, but they also showed enhanced cytocompatibility; we found a coefficient of thermal expansion of 12.8 ppm/°C and cell viability of 91.55 for the 65.1 vol% glass fiber‐reinforced PBZ composite. Moreover, samples reinforced with higher glass fiber loadings effectively resulted in the reduction of stress distribution in dentin observed from FEA suggesting protection againt root fractures. Restoration using the PBZ composite post showed the same stress patterns in the dentin‐composite resin‐post interface of the repaired tooth as in the natural tooth model. The results revealed that the glass fiber‐reinforced PBZ composites possess good thermal properties and mechanical behaviors which renders them suitable candidates for biocompatible dental materials.Highlights The glass fiber/polybenzoxazine (GF/PBZ) composites had nontoxic properties as evidenced through cell viability, growth and morphology studies. The thermal expansion of the GF/PBZ composite was similar to that of dentin, promoting adaptation at the dentin‐post interface. Mechanical behaviors evaluated by FEA of tooth model restored with GF/PBZ composite post were similar to those restored with commercial glass fiber post. The biocompatible GF/PBZ composite with good thermal and mechanical properties is a promising new candidate material as dental fiber post.

DNA damage (8-OHdG) and telomere length in captive Psittacidae birds with different longevity.

Aging is a complex process influenced by internal and external factors. Oxidative stress damages DNA, leading to 8-hydroxy-2' deoxyguanosine formation (8-OHdG). Telomere shortening is considered a biomarker of aging and oxidative stress may enhance its attrition. The ability to manage and repair oxidative stress varies among species and life histories. Avian species, such as Psittacidae birds, exhibit exceptional lifespans despite their physiological characteristics that might suggest otherwise. This study investigates 8-OHdG levels in serum samples from long- and short-lived birds of the order Psittaciformes, examining their relationship with telomere length and antioxidant capacity based on lifespan strategies. Among 43 individuals analyzed 26 belonged to the "long-lived species" group and 17 belonged to the "short-lived species" one. Relative telomere length (rTL) was measured in DNA isolated from whole blood by qPCR, and oxidative stress markers, such as Total Antioxidant Capacity (TAC) and 8-OHdG, were determined by spectrophotometry in serum samples. Long-lived birds had longer rTL than short-lived ones [1.308 ± 0.11 vs. 0.565 ± 0.13, (p < 0.001)]. On the contrary, short-lived birds showed more DNA damage than their counterparts [3.847 ± 0.351 vs. 2.012 ± 0.308, respectively, (p < 0.001)]. Old birds had shorter rTL than young ones, for both longevity groups (p < 0.001). Although no correlation was found between 8-OHdG levels and age, nor 8-OHdG and telomere length, long-lived birds exhibited 75.42-unit increased TAC levels when increased 8-OHdG concentrations (p = 0.046). These findings highlight distinct patterns of telomere length and oxidative stress influenced by lifespan strategies among avian longevity groups.

Development of idealized human aortic models for in vitro and in silico hemodynamic studies.

The aorta, a central component of the cardiovascular system, plays a pivotal role in ensuring blood circulation. Despite its importance, there is a notable lack of idealized models for experimental and computational studies. This study aims to develop computer-aided design (CAD) models for the idealized human aorta, intended for studying hemodynamics or solid mechanics in both in vitro and in silico settings. Various parameters were extracted from comprehensive literature sources to evaluate major anatomical characteristics of the aorta in healthy adults, including variations in aortic arch branches and corresponding dimensions. The idealized models were generated based on averages weighted by the cohort size of each study for several morphological parameters collected and compiled from image-based or cadaveric studies, as well as data from four recruited subjects. The models were used for hemodynamics assessment using particle image velocimetry (PIV) measurements and computational fluid dynamics (CFD) simulations. Two CAD models for the idealized human aorta were developed, focusing on the healthy population. The CFD simulations, which align closely with the PIV measurements, capture the main global flow features and wall shear stress patterns observed in patient-specific cases, demonstrating the capabilities of the designed models. The collected statistical data on the aorta and the two idealized aorta models, covering prevalent arch variants known as Normal and Bovine types, are shown to be useful for examining the hemodynamics of the aorta. They also hold promise for applications in designing medical devices where anatomical statistics are needed.

Research on Key Parameters for Relieving Pressure on Roofs of Deep Mine Cutting and Retaining Roadways

Scientific and reasonable roof-cutting parameters are key to ensuring pressure relief of the retained roadway roof. This manuscript takes the 7135 working face of Qidong Coal Mine as the engineering background and uses theoretical analysis, numerical and on-site measurement methods to study the quantitative relationship and pressure relief effect between different roof-cutting parameters of GERRC. We established a fracture criterion based on the tensile strength of the main roof of the uncut joint along the cutting line. We analyzed the quantitative relationship between different main roof thickness, cutting height, cutting angle, and the main roof tensile stress of the uncut joint. We found that within a small range of cutting angles, as the cutting angle decreases, the tensile stress on the main roof of the uncut joint increases. When the cutting angle is 0, the main roof tensile stress of the uncut joint reaches its maximum. As the cutting height increases, the limitation of the cutting angle on the cutting height becomes smaller. Numerical simulation was conducted to study the distribution patterns of maximum and minimum principal stresses along the direction of the roadway roof during the retention period under different roof-cutting heights and angles. Based on this, the optimal unloading effect of the roadway roof and the minimum concentration of mining stress were obtained at a roof-cutting height of 9 m and a roof-cutting angle of 80°. Through on-site measurement of the stress on the reinforcement anchor cable during the retention period, the deformation of the sinking roadway roof, and the pressure relief control effect of the retained roadway roof, the pressure relief effect and scientific rationality of the design of the cutting height and cutting angle were verified.

Effects of Mindfulness App on Parental Stress &amp; Sleep

Abstract Date Presented 03/22/24 This study explored the effects of a 4-week mindfulness app-based intervention on measures of parental stress, sleep, and sensory processing patterns. Primary Author and Speaker: Megan C. C. Chang Additional Authors and Speakers: Emily Boykin, Molly Cluff, Devin Cornish, Laura Labrador, Winnie Lee, Taylor McLaughlin

To Evaluate the Favourable Distribution Pattern of Stress in Maxilla and Mandible during Maxillary Protraction Using Miniplates of Varying Diameters and Thread Pitches under Different Levels of Inter Maxillary Forces: A Study Using Finite Element Analysis

Introduction The aim of the study is to compare the stress distribution pattern by three different diameters of miniplate (1.5 mm, 2 mm, 2.5 mm) of three different mini- implant thread pitches (0 .5 mm, 1 mm, 1.5 mm), in the maxilla and mandible during maxillary protraction using different inter-maxillary elastic force of (2 N,4N,6N,8 N).  Materials and Methods Using Autocad software and plate geometry, a 3D finite element model of the maxilla was made with a miniplate at the infrazygomatic buttress and a mandibular miniplate at the mandibular parasymphysis. Stress distributions and displacements were analyzed in Von Mises stress form using Ansys software.  Results In the implant study, the Von Mises stress in bone (Mpa) was 142 Mpa for the 1 mm diameter implant, which was the lowest compared to 170 Mpa for the 0.5 mm pitch and 233 Mpa for the 1.5 mm pitch. Whereas in skull study when 2N elastic force was applied for a 2 mm diameter minimplant, the maximum Von Mises stress at 0.5mm,1mm and 1.5mm thread pitch was (18.454 Mpa, 18.47 Mpa, and 18.344 Mpa. For elastic force of 4N was (18,465 Mpa, 18.492 Mpa and 18.244 Mpa), for 6N elastic force was 18.388 Mpa, 18.43 Mpa and 18.086 Mpa), and for 8N was (18.272 Mpa, 18.324 Mpa and 17.883 Mpa), which was similar compared from other two diameters.  Conclusion When comparing 1.5 mm, 2 mm, and 2.5 mm diameter implants with 0.5 mm, 1 mm, and 1.5 mm pitch thread , the 2 mm diameter at 1 mm pitch thread shows the least strained bone in the implant study. Whereas,in the skull study, 2 mm diameter mini-implants had similar stress distribution in the maxilla and mandible,in all the thread pitches and elastic force which shows pitch variants and different force application is not a factor for stress distribution in the bone.

Bite hard: Linking cranial loading mechanics to ecological differences in gnawing behavior in caviomorph rodents.

The mammalian skull is very malleable and has notably radiated into highly diverse morphologies, fulfilling a broad range of functional needs. Although gnawing is relatively common in mammals, this behavior and its associated morphology are diagnostic features for rodents. These animals possess a very versatile and highly mechanically advantageous masticatory apparatus, which, for instance, allowed caviomorph rodents to colonize South America during the Mid-Eocene and successfully radiate in over 200 extant species throughout most continental niches. Previous work has shown that differences in bite force within caviomorphs could be better explained by changes in muscle development than in mechanical advantages (i.e., in cranial overall morphology). Considering the strong bites they apply, it is interesting to assess how the reaction forces upon the incisors (compression) and the powerful adductor musculature pulling (tension) mechanically affect the cranium, especially between species with different ecologies (e.g., chisel-tooth digging). Thus, we ran finite element analyses upon crania of the subterranean Talas' tuco-tuco Ctenomys talarum, the semi-fossorial common degu Octodon degus, and the saxicolous long-tailed chinchilla Chinchilla lanigera to simulate: (A) invivo biting in all species, and (B) rescaled muscle forces in non-ctenomyid rodents to match those of the tuco-tuco. Results show that the stress patterns correlate with the mechanical demands of distinctive ecologies, on invivo-based simulations, with the subterranean tuco-tuco being the most stressed species. In contrast, when standardizing all three species (rescaled models), non-ctenomyid models exhibited a several-fold increase in stress, in both magnitude and affected areas. Detailed observations evidenced that this increase in stress was higher in lateral sections of the snout and, mainly, the zygomatic arch; between approximately 2.5-3.5 times in the common degu and 4.0-5.0 times in the long-tailed chinchilla. Yet, neither species, module, nor simulation condition presented load factor levels that would imply structural failure by strong, incidental biting. Our results let us conclude that caviomorphs have a high baseline for mechanical strength of the cranium because of the inheritance of a very robust "rodent" model, while interspecific differences are associated with particular masticatory habits and the concomitant level of development of the adductor musculature. Especially, the masseteric and zygomaticomandibular muscles contribute to >80% of the bite force, and therefore, their contraction is responsible for the highest strains upon their origin sites, that is, the zygomatic arch and the snout. Thus, the robust crania of the subterranean and highly aggressive tuco-tucos allow them to withstand much stronger forces than degus or chinchillas, such as the ones produced by their hypertrophied jaw adductor muscles or imparted by the soil reaction.

Modeling and Laboratory Investigation of Tack Coats as Bituminous Pavement Interlayer

The adhesive properties of tack coats between asphalt pavement layers are crucial for the pavement’s structural behavior. This study first involved numerical analyses to compare stress patterns, deformations, and displacements in the pavement structure under various geometric and mechanical conditions. A rational calculation method based on the theory of elastic multilayer systems was used to quantify the impact of layer properties such as thickness, stiffness modulus, and Poisson’s ratio on interlayer bonding. Three bonding conditions—Full Friction, Partial Bonding, and Full Debonding—were analyzed to understand the tack coat’s effect between the top two layers. The second phase involved characterizing the mechanical behavior of the interface through shear strength tests (Leutner shear test) on both laboratory-prepared specimens and samples from a 10-year-old highway. Specimens were prepared using a Roller Compactor and tested under different interface conditions: hot-on-hot (H/H), residual bitumen 200 g/m2 (RB 200), and residual bitumen 400 g/m2 (RB 400). The tests examined the bonding effects in terms of tangential force and shear displacement at failure, as well as the impact of vehicular traffic on rutting and fatigue failure. Finally, this study investigated the long-term aging effects of the binder on interlayer bonding and sought to correlate the results of numerical calculations with those of the laboratory tests.

Calcite e-twins as a tectonic indicator, paleo stress pattern and structural evolution of the Zagros hinterland, SE Iran

Through the examination of calcite twins, this research outlines the tectonic development and paleo stress patterns of the Paleozoic Routshon complex situated in the southeastern segment of the Sanandaj–Sirjan zone, a hinterland region of the Zagros orogeny in southeastern Iran. The study of orogenic phase indicates that the deformation event affecting the southern sector of the Sanandaj-Sirjan zone aligns with the Cimmerian orogenic phase of the Late Triassic period. A variety of structural features at both map and outcrop scales highlight the importance of slip partitioning in the structural evolution of this region, driven by inclined transpression. Observations suggest that the deformation related to contractional components includes steeply to moderately plunging folds, dip-slip domain deformation primarily involving thrusts, and ongoing deformation by strike-slip component motion, which results in thrust-related ductile shear zones. The analysis of calcite c-axis fabrics from mylonite samples obtained from these shear zones indicates a low-temperature monoclinic pattern of non-coaxial deformation. This deformation type underscores the impact of the strike-slip component in the development of progressive simple shear within thrust-related shear zones in this segment of the Sanandaj-Sirjan zone. Dynamic analysis of c-axis fabric data reveals a NE-SW orientation for the principal compressive axes (σ1) in this area. This direction, corroborated by additional data such as fault surface, GPS, and earthquake focal mechanism data, confirms that the orientation of the compressive axes (σ1) has remained consistent from the Late Triassic to the present.

Clinical and inflammatory features of traffic-related diesel exposure in children with asthma

BackgroundEpidemiologic studies have revealed associations between traffic-related pollutants such as diesel particulate matter (PM) and asthma outcomes in children, but the inflammatory features associated with diesel PM exposure in children with asthma are not understood. ObjectiveTo evaluate symptoms, exacerbations, and lung function measures in children with uncontrolled asthma and their associations with residential proximity to major roadways and to determine associations between diesel PM exposure and systemic inflammatory cytokines, circulating markers of T-cell activation and exhaustion, and metabolomic features using biomarker studies. MethodsChildren 5 to 17 years of age with physician-diagnosed, uncontrolled asthma despite treatment with an asthma controller medication completed a research visit involving questionnaires, lung function testing, and venipuncture for biomarker studies. Geocoding was performed to quantify residential proximity to major roadways and pollutant exposure. ResultsA total of 447 children with uncontrolled asthma were enrolled. Children living closer to highly trafficked roadways were more disadvantaged and had more exposure to diesel PM, more exacerbations prompting an emergency department visit, and lower lung function measures. Children with the highest diesel PM exposure, compared with children with the lowest diesel PM exposure, also had blunted cytokine secretion and evidence of T-cell exhaustion, including disturbances in several metabolites associated with glutathione formation and oxidative stress. ConclusionTraffic-related diesel PM exposure in children with poorly controlled asthma is associated with poorer clinical outcomes and unique patterns of inflammation and oxidative stress. These findings argue for continued mitigation efforts to improve traffic-related air quality and health equity in children with asthma.

Polyploidy and environmental stress response: a comparative study of fern gametophytes.

Climate change is rapidly altering natural habitats and generating complex patterns of environmental stress. Ferns are major components of many forest understories and, given their independent gametophyte generation, may experience unique pressures in emerging temperature and drought regimes. Polyploidy is widespread in ferns and may provide a selective advantage in these rapidly changing environments. This work aimed to understand whether the gametophytes of allopolyploid ferns respond differently to climate-related physiological stress than their diploid parents. The experimental approach involved a multifactorial design with 27 treatment combinations including exposure to multiple levels of drought and temperature over three treatment durations, with recovery measured at multiple timepoints. We measured Chl fluorescence from over 2000 gametophytes to evaluate stress avoidance and tolerance in diploid and polyploid species. Polyploids generally showed a greater ability to avoid and/or tolerate a range of stress conditions compared with their diploid counterparts, suggesting that polyploidy may confer enhanced flexibility and resilience under climate stress. Overall, these results suggest that polyploidy may provide some resilience to climate change in mixed ploidy populations. However, all species remain susceptible to the impacts of extreme drought and heat stress.