A Procedure to Measure the in-Situ Hygrothermal Behavior of Earth Walls

Rammed earth is a sustainable material with low embodied energy. However, its development as a building material requires a better evaluation of its moisture-thermal buffering abilities and its mechanical behavior. Both of these properties are known to strongly depend on the amount of water contained in wall pores and its evolution. Thus the aim of this paper is to present a procedure to measure this key parameter in rammed earth or cob walls by using two types of probes operating on the Time Domain Reflectometry (TDR) principle. A calibration procedure for the probes requiring solely four parameters is described. This calibration procedure is then used to monitor the hygrothermal behavior of a rammed earth wall (1.5 m × 1 m × 0.5 m), instrumented by six probes during its manufacture, and submitted to insulated, natural convection and forced convection conditions. These measurements underline the robustness of the calibration procedure over a large range of water content, even if the wall is submitted to quite important temperature variations. They also emphasize the importance of gravity on water content heterogeneity when the saturation is high, as well as the role of liquid-to-vapor phase change on the thermal behavior.     

Critères objectifs de gravité en cas d’hémorragie grave du post-partum : à propos de 310 cas

ObjectivesPostpartum haemorrhage (PPH) is a major contributor to maternal morbidity and mortality in France. The objective of our study was to reveal predictive factors of severity or cure, allowing an adapted management as less invasive as possible, in case of severe PPH.Patients and methodsThis retrospective study included 310 patients, who had been treated for a severe PPH in Lariboisière university hospital from April 2007 to April 2009.ResultsThe predictive factors found for an invasive management (surgery or embolization) are: at clinical examination, heart rate (88 versus 100 pulses per minute), importance of bleeding and the tonicity of the uterine globe. At biological examination, they are haemoglobin level (9 versus 8.2 g/dL) and clotting factors, especially fibrinogen (3 versus 2 g/L) and prothrombin time (PT) (76 versus 63%). The identified cure factors are the same ones as severity factors. With multivariate analysis, initial independent predictive factors about an invasive management were: the tonicity of the uterine globe (OR = 0.14), heart frequency (OR = 1.3) and PT (OR = 0.76).Discussion and conclusionIn case of severe haemorrhage, there may be the question of transfer of the patient. The difficulty is to avoid unnecessary transport, without delay for the future care. Very few studies searched predictive factors of severity or cure. Our study found, as predictive factors of invasive treatment, elements of physical examination (heart rate and the tonicity of the uterine globe) and biological factors (hemoglobin level and clotting factors).     

The neuromuscular fatigue induced by repeated scrums generates instability that can be limited by appropriate recovery

The aim of this study was to evaluate the influence of the fatigue on the machine scrum pushing sagittal forces during repeated scrums and to determine the origin of the knee extensor fatigue. Twelve elite U23 rugby union front row players performed six 6-s scrums every 30 s against a dynamic scrum machine with passive or active recovery. The peak, average, and the standard deviation of the force were measured. A neuromuscular testing procedure of the knee extensors was carried out before and immediately after the repeated scrum protocol including maximal voluntary force, evoked force, and voluntary activation. The average and peak forces did not decrease after six scrums with passive recovery. The standard deviation of the force increased by 70.2 ± 42.7% (P < 0.001). Maximal voluntary/evoked force and voluntary activation decreased (respectively 25.1 ± 7.0%, 14.6 ± 5.5%, and 24 ± 9.9%; P < 0.001). The standard deviation of the force did not increase with active recovery and was associated with lower decrease of maximal voluntary/evoked force and voluntary activation (respectively 12.8 ± 7.9%, 4.9 ± 6.5%, and 7.6 ± 4.1%; all P < 0.01). As a conclusion repeated scrummaging induced an increased machine scrum pushing instability associated with central and peripheral fatigue of the knee extensors. Active recovery seems to limit all these manifestations of fatigue.