Characterization and sorption properties of low pH cements

Characterization of three low pH cement pastes, including the description of their sorption properties for tritiated water (HTO), 36Cl- and 129I- is described in this work. SEM-EDX and NMR analyses show that after 90 days of hydration, the main hydrated phases are C-S-H and C-A-S-H gels with a Ca:Si ratio between 0.8 - 1.0 and a Al:Si ratio of 0.05. TG-DSC and XRD indicate the presence of calcite in the mixtures where limestone filler has been used. Additional techniques were used to identify minor hydrated solid phases like ettringite (i.e., XRD and solid state NMR). Porosity and pore size distribution was characterized by MIP observing that the size of the pores in the hydrated cement phases varies from the micro to the nanoscale. Uptake studies of HTO, 36Cl- and 129Ifrom batch sorption experiments indicate very weak sorption (Kd < 0.40 ± 0.13 L/kg) for the 3 selected radionuclides. The uptake process of 36Cl- and 129I- is probably associated with surface processes in the C-S-H and C-A-S-H phases with competition for sorption sites, between them. In the case of HTO, isotopic exchange with the interlayer water of the C-S-H and the C-A-S-H seems to be the main uptake process

The speed prior account: a new theory to explain multiple phenomena regarding dynamic information

Our perception of moving stimuli is prone to systematic biases. Different biases, for example concerning the perceived speed, or spatial location, of a dynamic, moving stimulus, have consistently been reported in the literature. Different lines of experimental research, together with different theoretical explanations, have emerged analysing and discussing these biases separately. In the present study, we propose a new theoretical account to unite various effects relating to dynamic / moving stimuli: The speed prior account. The perceived location of a stimulus is suggested to reflect the combination of the sensory input, which is associated with uncertainty, and a prior expectation concerning stimulus speed. Discrepancies between the prior speed expectation and the actual speed of a stimulus then result in a distortion of perceived stimulus speed, leading to the various perceptual biases that have been observed. In the present study, we demonstrate that this new theory can already account for robust data patterns currently unexplained in the literature, while we additionally directly test the predic-tions of the new speed prior account across four experiments. The influence of stimulus speed was manipulated in two visual, as well as two tactile studies (all N = 30). The results reveal a clear data pattern, consistent with the speed prior account, as perceived onset and offset location reveal strong interdependencies. The implications and possible future ques-tions for the perception of moving stimuli, in particular, and dynamic information, more generally, are discussed

The speed prior account: a new theory to explain multiple phenomena regarding dynamic information

Our perception of moving stimuli is prone to systematic biases. Different biases, for example concerning the perceived speed, or spatial location, of a dynamic, moving stimulus, have consistently been reported in the literature. Different lines of experimental research, together with different theoretical explanations, have emerged analysing and discussing these biases separately. In the present study, we propose a new theoretical account to unite various effects relating to dynamic / moving stimuli: The speed prior account. The perceived location of a stimulus is suggested to reflect the combination of the sensory input, which is associated with uncertainty, and a prior expectation concerning stimulus speed. Discrepancies between the prior speed expectation and the actual speed of a stimulus then result in a distortion of perceived stimulus speed, leading to the various perceptual biases that have been observed. In the present study, we demonstrate that this new theory can already account for robust data patterns currently unexplained in the literature, while we additionally directly test the predic-tions of the new speed prior account across four experiments. The influence of stimulus speed was manipulated in two visual, as well as two tactile studies (all N = 30). The results reveal a clear data pattern, consistent with the speed prior account, as perceived onset and offset location reveal strong interdependencies. The implications and possible future ques-tions for the perception of moving stimuli, in particular, and dynamic information, more generally, are discussed