A summary of pain and pain-related variables in the Avon Longitudinal Study of Parents and Children

To study pain, data on pain characteristics, possible triggers and consequences - such as the impact of pain on people's lives - need to be available. When not collated, described and/or organised in a systematic manner, it can be difficult to assess how useful an existing dataset may be for one's project. This data note describes and categorises the complex and multi-modal indices of pain available in the Avon Longitudinal Study of Parents and Children (ALSPAC). Data from two generations of the ALSPAC cohort; index child participants (Generation 1, G1), their mothers and fathers/mothers' partners (Generation 0, G0) were used. Search terms such as 'pain', 'ache', 'hurt', 'sore', specific pain conditions, labour pain and methods of pain relief were used to identify pain and pain-related variables. These data were extracted from all waves of data collection. We developed pain categories and subsequently categorised variables in an iterative process. Repeated measurements of the same variables over waves of data collection were also identified. We identified 21 categories of pain variables, which were subsequently grouped into themes: pain characteristics, extended pain characteristics and causes, treatment for pain, pain interference and pain-related to specific events. Pain and pain-related data have been collected from G1 participants, G0 mothers, and G0 partners, although there are fewer data for the partners. There were some repeated measurements, most commonly, of pain location. As is typical with longitudinal birth cohort studies, maternal proxy-reports were used during participants' younger years and self-reports were utilised from adolescence onwards. Researchers interested in studying pain can feasibly do so in two generations of a regional UK population who have been followed up over 30 years. ALSPAC can be used to study pain from the early years through to young adulthood and in mothers from the perinatal period onwards. [Abstract copyright: Copyright: © 2024 Ly A et al.

About the heat sources generated during fatigue crack growth: What consequences on the stress intensity factor?

During cyclic loading of a cracked metallic alloy at room temperature, heat sources are generated and produce a heterogeneous temperature field around the crack tip. Those heat sources are: (i) the thermo-elastic coupling source, (ii) the intrinsic dissipation due to microplasticity in the material, and (iii) the cyclic plasticity dissipated into heat in the reverse cyclic plastic zone (RCPZ) ahead of the crack tip. The thermoelastic source is computed by finite element analysis in agreement with classic linear thermoelasticity theory. The intrinsic dissipation due to microplasticity is experimentally estimated by carrying out self-heating fatigue tests on uncracked specimens, and then approximating its values in the cracked specimens by using self-heating curves. The cyclic plastic strain energy dissipated into heat in the RCPZ is also experimentally quantified by carrying out fatigue crack growth tests and using infrared measurements. The temperature fields, generated by the three types of heat sources, are separately computed by using the linearity of the heat diffusion equation. Afterward, the stress fields, associated with each thermal effect and induced by the material thermal expansion, are computed by considering the hypothesis of the linear elastic fracture mechanics (LEFM). Thus, the mode I stress intensity factor is calculated by taking into account the thermal effect associated with each heat source. The consequenceson K, DK and RK = Kmin/Kmax are discussed. It is shown that the heat sources do not modify significantly DK, but the modification of RK can be significant since the effects are proportionalto the loading frequency.Bourse Ecole Doctorale ENSA

Experimental Investigation of an Infrared Deicing System for Wind Power Application in a Cold Climate

Icing of wind turbine blades poses a great challenge for wind farms in cold climates, this challenge is addressed by implementing various deicing practices that require significant cost to operate. Thus, alternative and potential solutions are needed to improve wind power production in cold climate. The present study is investigates the effectiveness of a new deicing system consisting of infrared heaters. Two types of heaters were selected based on wavelength, input power, and investment cost. The heaters were tested on blades covered with soft rime ice. A thermal camera was used to image the deicing procedure together with a load cell to measure the weight of the ice melted. It was found that a combination of two different types of heaters provides effective deicing at a distance of 1.5 m compared with multiple units of the same type of heaters. It was observed that the infrared deicing system has a larger area of heat distribution, which is one of the major advantages compared with traditional systems. © 2022 American Society of Civil Engineers.</p