Estimation of root water uptake parameters by inverse modeling with soil water content data

In this paper we have tested the feasibility of the inverse modeling approach to derive root water uptake parameters (RWUP) from soil water content data using numerical experiments for three differently textured soils and for an optimal drying period. The RWUP of interest are the rooting depth and the bottom root length density. In a first step, a thorough sensitivity analysis was performed. This showed that soil water content dynamics is relatively insensitive to RWUP and that the sensitivity depends on the texture of the considered soil. For medium-fine textured soil, the sensitivity is particularly low due to relatively high unsaturated hydraulic conductivity values. These ones allow a “compensating effect” to occur, i.e., vertical unsaturated water fluxes overshadowing in some way the root water uptake. In a second step, we analyzed the well-posedness of the solution (stability and nonuniqueness) when only RWUP are optimized. For this case, the inverse problem is clearly ill-posed except for the estimation of the rooting depth parameter for coarse and the very fine textured soils. In a third step, we addressed the case where RWUP are estimated simultaneously with additional parameters of the system (i.e., with soil hydraulic parameters). For this case, our study showed that the inverse problem is well-posed for the coarse and very fine textured soils, allowing for the estimation of both RWUP of interest provided that a powerful global optimization algorithm is used. On the contrary, the estimation of RWUP is unfeasible for medium-fine textured soil due to the “compensating effect” of the vertical unsaturated water flows. In conclusion, we can state that the inverse modeling approach can be applied to derive RWUP for some soils (coarse and very fine textured) and that the feasibility is strongly improved if the RWUP are simultaneously optimized with additional parameters. Nevertheless, more detailed research is needed to apply the inverse modeling approach to real cases for which additional issues are likely to be encountered such as soil heterogeneity and root dynamics

Multiscale entropy-based analyses of soil transect data

A deeper understanding of the spatial variability of soil properties and the relationships between them is needed to scale up measured soil properties and to model soil processes. The object of this study was to describe the spatial scaling properties of a set of soil physical properties measured on a common 1024-m transect across arable fields at Silsoe in Bedfordshire, east-central England. Properties studied were volumetric water content ({theta}), total porosity ({pi}), pH, and N2O flux. We applied entropy as a means of quantifying the scaling behavior of each transect. Finally, we examined the spatial intrascaling behavior of the correlations between {theta} and the other soil variables. Relative entropies and increments in relative entropy calculated for {theta}, {pi}, and pH showed maximum structure at the 128-m scale, while N2O flux presented a more complex scale dependency at large and small scales. The intrascale-dependent correlation between {theta} and {pi} was negative at small scales up to 8 m. The rest of the intrascale-dependent correlation functions between {theta} with N2O fluxes and pH were in agreement with previous studies. These techniques allow research on scale effects localized in scale and provide the information that is complementary to the information about scale dependencies found across a range of scale

The influence of conceptual (mis)match on collaborative referring in dialogue

When two dialogue partners need to refer to something, they jointly negotiate which referring expression should be used. If needed, the chosen referring expression is then reused throughout the interaction, which potentially has a direct, positive impact on subsequent communication. The purpose of this study was to determine if the way in which the partners view, or conceptualise, the referent under discussion, affects referring expression negotiation and subsequent communication. A matching task was preceded by an individual task during which participants were required to describe their conceptualisations of abstract tangram pictures. The results revealed that participants found it more difficult to converge on single referring expression during the matching task when they initially held different conceptualisations of the pictures. This had a negative impact on the remainder of the task. These findings are discussed in light of the shared versus mutual knowledge distinction, highlighting how the former directly contributes to the formation of the latter

Do users’ reading skills and difficulty ratings for texts affect choices and evaluations?

In our contribution, we consider how corpus data can be used as a proxy for the written language environment around us in constructing offline studies of native-speaker intuition and usage. We assume a broadly emergent perspective on language: in other words, the linguistic competence of individuals is not identical or hardwired but forms gradually through exposure and coalescence of patterns of production and reaction. We hypothesize that while users presumably all in theory have access to the same linguistic material, their actual exposure to it and their ability to interpret it may differ, which will result in differing judgments and choices. Our study looks at the interaction between corpus frequency and two possible indicators of individual difference: attitude towards reading tasks and performance on reading tasks. We find a small but consistent effect of task performance on respondents’ judgments but do not confirm any effects on respondents’ production tasks

Effects of semantic variables on the subject-verb agreement processes in writing

Two experiments are reported in which participants were orally presented with French sentences that they were required to write down. In a single-task condition, only single sentences were presented and the written recall concerned only these sentences. In a dual-task condition, a second task was added: to memorize an additional list of words or to do mental addition while writing down the sentences. The experimental sentences were all of the type 'Prep. + N1 + verb + subject' (e.g. Dans les trains passe le controleur, Along the trains comes the inspector) in which the preverbal noun constituted either a plausible or an implausible subject for the verb following. Results showed that: (a) number agreement was more likely to be correct when the preverbal noun was implausible as the subject of the sentence, (b) but when they had to transcribe sentences with an implausible preverbal noun, the participants' performance at a concurrent task was poorer. These two findings indicate that the plausibility of the subject role of the preverbal noun provides information that can be used to control the procedures which underlie the construction of the agreement