Heat-related Changes Research Articles

Heat-related changes in the velocity and kinetic energy of flowing blood influence the human heart's output during hyperthermia.

Passive whole-body hyperthermia increases limb blood flow and cardiac output ( ), but the interplay between peripheral and central thermo-haemodynamic mechanisms remains unclear. Here we tested the hypothesis that local hyperthermia-induced alterations in peripheral blood flow and blood kinetic energy modulate flow to the heart and . Body temperatures, regional (leg, arm, head) and systemic haemodynamics, and left ventricular (LV) volumes and functions were assessed in eight healthy males during: (1) 3h control (normothermic condition); (2) 3h of single-leg heating; (3) 3h of two-leg heating; and (4) 2.5h of whole-body heating. Leg, forearm, and extracranial blood flow increased in close association with local rises in temperature while brain perfusion remained unchanged. Increases in blood velocity with small to no changes in the conduit artery diameter underpinned the augmented limb and extracranial perfusion. In all heating conditions, increased in association with proportional elevations in systemic vascular conductance, related to enhanced blood flow, blood velocity, vascular conductance and kinetic energy in the limbs and head (all R2≥0.803; P<0.001), but not in the brain. LV systolic (end-systolic elastance and twist) and diastolic functional profiles (untwisting rate), pulmonary ventilation and systemic aerobic metabolism were only altered in whole-body heating. These findings substantiate the idea that local hyperthermia-induced selective alterations in peripheral blood flow modulate the magnitude of flow to the heart and through changes in blood velocity and kinetic energy. Localised heat-activated events in the peripheral circulation therefore affect the human heart's output. KEY POINTS: Local and whole-body hyperthermia increases limb and systemic perfusion, but the underlying peripheral and central heat-sensitive mechanisms are not fully established. Here we investigated the regional (leg, arm and head) and systemic haemodynamics (cardiac output: ) during passive single-leg, two-leg and whole-body hyperthermia to determine the contribution of peripheral and central thermosensitive factors in the control of human circulation. Single-leg, two-leg, and whole-body hyperthermia induced graded increases in leg blood flow and . Brain blood flow, however, remained unchanged in all conditions. Ventilation, extracranial blood flow and cardiac systolic and diastolic functions only increased during whole-body hyperthermia. The augmented with hyperthermia was tightly related to increased limb and head blood velocity, flow and kinetic energy. The findings indicate that local thermosensitive mechanisms modulate regional blood velocity, flow and kinetic energy, thereby controlling the magnitude of flow to the heart and thus the coupling of peripheral and central circulation during hyperthermia.

Medico-legal scene investigation in the case of burned bodies - a systematic review.

A judicial on-site examination is essential for the correct analysis of a forensic case, particularly when there has been a fatal fire, as heat-related changes to bodies make identification by the forensic pathologist and other specialists difficult along with estimating the post-mortem interval and determining the precise cause and manner of death. We systematically reviewed all relevant articles dating from 2003 to 2022 in the PubMed database with a view to updating recommendations on how best to proceed. Our recommendations highlight the importance of a multidisciplinary team approach involving various forensic specialists.

Heat-related Changes of Density, P-wave Velocity, and Surface Hardness of Granite

Low- and intermediate-level radioactive waste is stored in the National Radioactive Waste Repository in Bátaapáti in Hungary. The repository is located in the Carboniferous Mórágy Granite Formation. This paper focuses on heat-related changes of physical properties such as bulk density, P-wave velocity, P-wave modulus, and Duroskop surface hardness of the dominant lithology: monzogranite. Cylindrical specimens were tested at laboratory conditions (22 °C) and were heat-treated up to 250 °C, 500 °C, and 750 °C. The properties were measured before and after the thermal strain. After heat-treatment, the monzogranite samples became brownish, and at 750 °C, cracks appear at the surface of the specimens. Laboratory test results show that bulk density values slightly decrease from room temperature to 250 °C treatment and further dropped at 500 °C and especially at 750 °C. P-wave velocity values and the connected P-wave modulus tend to decrease from room temperature to 750 °C significantly. Duroskop rebound values show slight declines in the surface strength of the specimens until 500 °C, and then a drastic decline at 750 °C. Heat treatment tends to alter the physical properties of the monzogranite. From room temperature to 500 °C, a slight but apparent decrease between 500 °C and 750 °C significant reductions in the bulk density, P-wave velocity, and Duroskop values. Behind the physical alterations are the different thermal-induced expansion of minerals and mineral alteration at elevated temperatures.

Colourimetric analysis of thermally altered human bone samples

At this moment, no method is available to objectively estimate the temperature to which skeletal remains have been exposed during a fire. Estimating this temperature can provide crucial information in a legal investigation. Exposure of bone to heat results in observable and measurable changes, including a change in colour. To determine the exposure temperature of experimental bone samples, heat related changes in colour were systemically studied by means of image analysis. In total 1138 samples of fresh human long bone diaphysis and epiphysis, varying in size, were subjected to heat ranging from room temperature to 900 °C for various durations and in different media. The samples were scanned with a calibrated flatbed scanner and photographed with a Digital Single Lens Reflex camera. Red, Green, Blue values and Lightness, A-, and B-coordinates were collected for statistical analysis. Cluster analysis showed that discriminating thresholds for Lightness and B-coordinate could be defined and used to construct a model of decision rules. This model enables the user to differentiate between seven different temperature clusters with relatively high precision and accuracy. The proposed decision model provides an objective, robust and non-destructive method for estimating the exposure temperature of heated bone samples.

The mountains are calling! An extended TPB model for understanding metropolitan residents' intentions to visit nearby alpine destinations in summer

This study investigated the suitability of an extended Theory of Planned Behaviour (TPB) to research the travel intention of metropolitan citizens to nearby destinations. The consideration of heat waves in this context is a novel approach. The survey data was collected from 877 Viennese respondents. Structural equation modelling shows a very good fit of the final model to the data; model extensions yield a strong increase of explained variance. The results suggest that heat-related change of intention is influenced by the strength of heat stress perceived during past heat waves. Nevertheless, subjective and social norm are the strongest determinants of intention, whereas attitude is a very weak predictor. Additional significant predictors are outdoor sports as a travel motive, media coverage, and past behaviour. The first application of an extended TPB model to summer tourism in the context of climate change yields important insights as to how climate change affects the destination choice of summer tourists. The results provide valuable starting points for attracting heat stressed metropolitan visitors.

Clinical findings in the medico-legal investigation of arsonists

Criminal and pathological arson is often committed with the help of fire accelerants. The formation of an explosive gas/air mixture may lead to an explosion whose extent and fierceness is often underestimated by the offenders. This explosion causes typical heat changes on exposed persons: • • Singeing of eyelashes, eyebrows and hair growing near the frontal hairline • • Singeing of the beard • • Singeing of body hair in regions not covered by clothing (e.g. back of the hand) • • In severe cases, skin burns of varying degree (back of hand, face). Such heat-related changes can sometimes be detected weeks after the offence.

Heat-related changes to the hydrophobicity of cheese whey correlate with levels of native beta-lactoglobulin and alpha-lactalbumin.

Correlations were identified between levels of the native whey proteins, beta-lactoglobulin and alpha-lactalbumin and the surface and total hydrophobicities of cheese whey in response to different heat treatments. Heat-induced changes in the native beta-lactoglobulin content and surface hydrophobicity of whey exhibited the most significant linear relationship while correlations between total hydrophobicity and the native proteins were less significant because of an atypical rise in the n-heptane-binding capacity of whey after high-temperature treatment. The content of native beta-lactoglobulin in whey was more sensitive to heating than the content of native alpha-lactalbumin, while heat-related changes in the total hydrophobicity of whey were generally greater than similar changes in surface hydrophobicity.