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"Stress history"
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Analytical method for laterally loaded piles in soft clay considering the influence of soil outside the scour hole on the effective overburden pressure
Scour reduces the effective overburden pressure and the undrained shear strength of soil, thus affecting the lateral load-bearing capacity of pile foundations. Compared with general scour, local scour can decrease the reduction of the effective overburden pressure and the undrained shear strength around the pile due to the existence of soil outside the scour hole. To fully reflect the actual situation at a site, the behavior of laterally loaded piles in soft clay should consider both the scour-hole dimensions and the soil stress history. This paper proposes a closed-form analytical solution for laterally loaded piles in soft clay that can simultaneously account for the changes in effective overburden pressure and undrained shear strength caused by the scour-hole dimensions and the soil stress history based on the p–y curve proposed by Matlock. The average reduced stress is introduced according to Boussinesq’s point load solution. Case studies demonstrate that the analytical method is reliable with reasonable accuracy. According to the parameter study, the load eccentricity is the most sensitive factor compared with the changes in soil properties caused by the scour-hole dimensions and the soil stress history.
Journal Article
Feeling the strain : a cultural history of stress in twentieth-century Britain
Examining the popular discourse of nerves and stress, this book provides a historical account of how ordinary Britons understood, explained and coped with the pressures and strains of daily life during the twentieth century. It traces the popular, vernacular discourse of stress, illuminating not just how stress was known, but the ways in which that knowledge was produced. Taking a cultural approach, the book focuses on contemporary popular understandings, revealing continuity of ideas about work, mental health, status, gender and individual weakness, as well as the changing socio-economic contexts that enabled stress to become a ubiquitous condition of everyday life by the end of the century. With accounts from sufferers, families and colleagues it also offers insight into self-help literature, the meanings of work and changing dynamics of domestic life, delivering a complementary perspective to medical histories of stress.
Book
A laboratory study on the thermomechanical behaviour of clayey soils
This paper presents the findings of a laboratory investigation of the thermomechanical behaviour of clayey soils. The tests were performed on reconstituted and natural clayey soils using triaxial cells modified to control temperature. The range of temperatures that were investigated is from 20° to 60°C. The thermal behaviour of the clays and the influence of temperature on their mechanical behaviour were investigated separately. The analysis of the experimental results obtained in drained and undrained nonisothermal tests and during thermal consolidation made it possible to identify a link between the thermal and the time-dependent behaviour of the soil skeleton. Therefore, as for creep processes, the response of the soil to thermal loading is not unique but among other factors depends strongly on the overall and recent stress history experienced by the soil. In the range of temperatures investigated, the deformability and strength of the soil were found to be relatively independent of temperature. Stiffening of the soil results from thermal cycles.Key words: clay, temperature, creep, stress history, recent stress history.
Journal Article
Effects of previous cyclic loading history on subsequent cyclic hehaviour of sand
Sand widely employed as subgrade materials, experience varying traffic-induced cyclic loads during service. This study investigates how prior loading history alters their subsequent cyclic deformation characteristics through multistage drained cyclic triaxial tests. Specimens underwent two-phase loading with controlled stress amplitude variations (increase, decrease, or maintenance) in the second stage. Key findings reveal: 1) Stress history critically governs deformation patterns—increased second-stage amplitude reactivates strain accumulation, while hysteresis loop reopening depends on the cumulative plastic strain from first-stage loading; Hysteresis loop reopening in subsequent loading is governed by whether prior deformation exceeds the first-cycle strain threshold observed in virgin sand under equivalent stress amplitude; A novel deformation model incorporating strain accumulation rates and equivalent cycle numbers quantitatively predicts stress-history effects. The proposed framework advances the mechanistic understanding of sand’s memory-dependent cyclic behavior, providing practical tools for infrastructure design under multistage traffic loading conditions.
Journal Article
Hystopia
\"By the early 1970s, President John F. Kennedy has survived several assassination attempts and--martyred, heroic--is now in his third term. Twenty-two-year-old Eugene Allen returns home from his tour of duty in Vietnam and begins to write a war novel--a book echoing Catch-22 and Slaughterhouse-Five--about veterans who have their battlefield experiences \"enfolded,\" wiped from their memories through drugs and therapy. In Eugene's fictive universe, veterans too damaged to be enfolded stalk the American heartland, reenacting atrocities on civilians and evading the Psych Corps, a federal agency dedicated to upholding the mental hygiene of the nation by any means necessary. This alternative America, in which a veteran tries to reimagine a damaged world, is the subject of Hystopia, the long-awaited first novel by David Means.\"-- Provided by publisher.
Book
Coral Thermal Tolerance: Tuning Gene Expression to Resist Thermal Stress
The acclimatization capacity of corals is a critical consideration in the persistence of coral reefs under stresses imposed by global climate change. The stress history of corals plays a role in subsequent response to heat stress, but the transcriptomic changes associated with these plastic changes have not been previously explored. In order to identify host transcriptomic changes associated with acquired thermal tolerance in the scleractinian coral Acropora millepora, corals preconditioned to a sub-lethal temperature of 3°C below bleaching threshold temperature were compared to both non-preconditioned corals and untreated controls using a cDNA microarray platform. After eight days of hyperthermal challenge, conditions under which non-preconditioned corals bleached and preconditioned corals (thermal-tolerant) maintained Symbiodinium density, a clear differentiation in the transcriptional profiles was revealed among the condition examined. Among these changes, nine differentially expressed genes separated preconditioned corals from non-preconditioned corals, with 42 genes differentially expressed between control and preconditioned treatments, and 70 genes between non-preconditioned corals and controls. Differentially expressed genes included components of an apoptotic signaling cascade, which suggest the inhibition of apoptosis in preconditioned corals. Additionally, lectins and genes involved in response to oxidative stress were also detected. One dominant pattern was the apparent tuning of gene expression observed between preconditioned and non-preconditioned treatments; that is, differences in expression magnitude were more apparent than differences in the identity of genes differentially expressed. Our work revealed a transcriptomic signature underlying the tolerance associated with coral thermal history, and suggests that understanding the molecular mechanisms behind physiological acclimatization would be critical for the modeling of reefs in impending climate change scenarios.
Journal Article
Scales Tell a Story on the Stress History of Fish
Fish faced with stressful stimuli launch an endocrine stress response through activation of the hypothalamic-pituitary-interrenal (HPI-) axis to release cortisol into the blood. Scientifically validated biomarkers to capture systemic cortisol exposure over longer periods of time are of utmost importance to assess chronic stress in governmental, wildlife, aquaculture and scientific settings. Here we demonstrate that cortisol in scales of common carp (Cyprinus carpio L.) is the long-sought biomarker for chronic stress. Undisturbed (CTR) and daily stressed (STRESS) carp were compared. Dexamethasone (DEX) or cortisol (CORT) fed fish served as negative and positive controls, respectively. Scale cortisol was quantified with a validated ultra-performance liquid chromatography tandem mass spectrometry method. An increase in scale cortisol content was found in STRESS and CORT but not in CTR and DEX fish. Scale cortisol content reflects its accumulation in a stressor and time dependent manner and validates the scale cortisol content as biomarker for chronic stress. Plasma analyses confirmed that (i) CTR, DEX and CORT treatments were effective, (ii) plasma cortisol of STRESS fish showed no signs of chronic HPI-axis activation, and (iii) plasma cortisol is a poor predictor for chronic stress. The expression of HPI key genes crf, pomc, and star were up-regulated in STRESS fish in the absence of a plasma cortisol response, as was the target gene of cortisol encoding subunit α1 of the Na+/K+-ATPase in gills. When lost, scales of fish regenerate fast. Regenerated scales corroborate our findings, offering (i) unsurpassed time resolution for cortisol incorporation and as such for stressful events, and (ii) the possibility to investigate stress in a well defined and controlled environment and time frame creating novel opportunities for bone physiological research. We conclude that the cortisol content in ontogenetic and regenerated scales is an innovative biomarker for chronic stress offering ample applications in science and industry.
Journal Article