This paper argues that current pragmatic theories fail to describe common ground in its complexity because they usually retain a communication-as-transfer-between-minds view of language, and disregard the fact that disagreement and egocentrism of speaker-hearers are as fundamental parts of communication as agreement and cooperation. On the other hand, current cognitive research has overestimated the egocentric behavior of the dyads and argued for the dynamic emergent property of common ground while devaluing the overall significance of cooperation in the process of verbal communication. The paper attempts to eliminate this conflict and proposes to combine the two views into an integrated concept of common ground, in which both core common ground (assumed shared knowledge, a priori mental representation) and emergent common ground (emergent participant resource, a post facto emergence through use) converge to construct a dialectical socio-cultural background for communication.Both cognitive and pragmatic considerations are central to this issue. While attention (through salience, which is the cause for interlocutors' egocentrism) explains why emergent property unfolds, intention (through relevance, which is expressed in cooperation) explains why presumed shared knowledge is needed. Based on this, common ground is perceived as an effort to converge the mental representation of shared knowledge present as memory that we can activate, shared knowledge that we can seek, and rapport, as well as knowledge that we can create in the communicative process. The socio-cognitive approach emphasizes that common ground is a dynamic construct that is mutually constructed by interlocutors throughout the communicative process. The core and emergent components join in the construction of common ground in all stages, although they may contribute to the construction process in different ways, to different extents, and in different phases of the communicative process.

Abstract. We present integrated colours, integrated spectral energy distributions, and absorption-line indices, for instantaneous burst solar-metallicity binary stellar populations with ages in the range 1−15 Gyr. By comparing the results for populations with and without binary interactions we show that the inclusion of binary interactions makes the appearance of the population substantially bluer -this is the case for each of the quantities we have considered. This effect raises the derived age and metallicity of the population. Therefore it is necessary to consider binary interactions in order to draw accurate conclusions from evolutionary population synthesis work.

Using evolutionary population synthesis we present integrated colours, integrated spectral energy distributions and absorption-line indices defined by the Lick Observatory image dissector scanner (referred to as the Lick/IDS) system, for an extensive set of instantaneous-burst binary stellar populations with and without binary interactions. The ages of the populations are in the range 1-15 Gyr and the metallicities are in the range 0.0001-0.03. By comparing the results for populations with and without binary interactions we show that the inclusion of binary interactions makes the integrated U-B, B-V, V-R and R-I colours and all Lick/IDS spectral absorption indices (except for H β ) substantially smaller. In other words, binary evolution makes a population appear bluer. This effect raises the derived age and metallicity of the population.We calculate several sets of additional solar-metallicity binary stellar populations to explore the influence of the binary evolution algorithm input parameters (the common-envelope ejection efficiency and the stellar wind mass-loss rate) on the resulting integrated colours. We also look at the dependence on the choice of distribution functions used to generate the initial binary population. The results show that variations in the choice of input model parameters and distributions can significantly affect the results. However, comparing the discrepancies that exist between the colours of various models, we find that the differences are less than those produced between the models with and those without binary interactions. Therefore it is very necessary to consider binary interactions in order to draw accurate conclusions from evolutionary population synthesis work.

We construct a parametrized model to explore the main properties of the star-formation history of M33. We assume that the disc originates and grows by primordial gas infall and adopt a simple form of gas accretion rate with one free parameter, the infall time-scale. We also include the contribution of the gas outflow process. A major update of the model is that we adopt a molecular-hydrogen-correlated star-formation law and calculate the evolution of the atomic and molecular gas separately. Comparisons between the model predictions and observational data show that the model predictions are very sensitive to the adopted infall time-scale, while the gas-outflow process mainly influences the metallicity profile. A model adopting a moderate outflow rate and an inside-out formation scenario can be in good agreement with most of the observed constraints of the M33 disc. We also compare model predictions based on a molecular-hydrogen-correlated star-formation law and that based on the Kennicutt starformation law. Our results imply that the molecular-hydrogen-correlated star-formation law should be preferred to describe the evolution of the M33 disc, especially the radial distributions of both the cold gas and the stellar population.

Well-determined physical parameters of 130 W UMa systems have been collected from the literature. Based on these data, the evolutionary status and dynamical evolution of W UMa systems are investigated. It is found that there is no evolutionary difference between W- and A-type systems in $M-J$ diagram which is consistent with the results derived from the analysis of observed spectral type, $M-R$ and $M-L$ diagrams of W UMa systems. $M-R$ and $M-L$ diagrams of W- and A-type systems indicate that a large amount of energy should be transferred from the more massive to the less massive component so that they are not in thermal equilibrium and undergo thermal relaxation oscillation (TRO). Meanwhile, the distribution of angular momentum, together with the distribution of mass ratio, suggests that the mass ratio of the observed W UMa systems is decreased with the decrease of their total mass. This could be the result of the dynamical evolution of W UMa systems which suffer angular momentum loss (AML) and mass loss due to magnetic stellar wind (MSW). Consequently, the tidal instability forces these systems towards the lower q values and finally to fast rotating single stars.Comment: 8 pages, 5 figures, accepted for publication in MNRA

Context. Colors are usually not used for constraining stellar populations because they are thought to have the well-known agemetallicity degeneracy, but some recent works show that colors can also be used. A simple stellar population synthesis model is widely used, but there is no analysis for its colors. Aims. We try to find colors that can potentially be used to determine the age and metallicity of stellar populations by the standard model. Methods. Principal component analysis and relative sensitive parameter techniques are used in this work. Results. U − K, U − H, U − J, B− K, B− H, U − I, B− J,and V − K are found to be more important for studying populations than others. Pairs of colors such as B− K and B−V are found to be able to disentangle the stellar age-metallicity degeneracy via the high-resolution model, while pairs such as U − K and R − I may be used instead when the low-resolution model is used. Furthermore, the u − g and r − i colors of the low-resolution model seem to have the same potential, but there are no such colors for the high-resolution one. Conclusions. Some colors have been shown to have the potential to determine the age and metallicity of stellar populations, but relative metallicity and age sensitivities of colors in different stellar population synthesis models are usually different. In addition, minor star formations will make star systems look younger and more metal rich than their dominating populations.

Using evolutionary population synthesis, we present high-resolution (0.3 Å) integrated spectral energy distributions from 3000 to 7000 Å and absorption-line indices defined by the Lick Observatory Image Dissector Scanner (Lick/IDS) system, for an extensive set of instantaneousburst binary stellar populations with binary interactions. The ages of the populations are in the range 1-15 Gyr and the metallicities are in the range 0.004-0.03. These high-resolution synthesis results can satisfy the needs of modern spectroscopic galaxy surveys, and are available on request.By comparing the synthetic continuum of populations at high and low resolution, we show that there is good agreement for solar metallicity and tolerable disagreement for non-solar metallicity. The strength of the Balmer lines at high spectral resolution is greater than that at low resolution for all metallicities. The comparison of Lick/IDS absorption-line indices at low and high resolution, both of which are obtained by the fitting functions, shows that the discrepancies in all indices except for TiO 1 and TiO 2 are insignificant for populations with Z = 0.004 and 0.02. The high-resolution Ca4227, Fe5015 and Mg b indices are redder than the corresponding low-resolution ones for populations with Z = 0.01 and 0.03; this effect lowers the derived age and metallicity of the population. The high-resolution Mg 1 , Fe5709 and Fe5782 indices are bluer than those at low resolution; this effect raises the age and metallicity. The discrepancy in these six indices is greater for populations with Z = 0.03 in comparison to Z = 0.01.At high resolution we compare the Lick/IDS spectral absorption indices obtained by using the fitting functions with those measured directly from the synthetic spectra. We find that the Ca4455, Fe4668, Mg b and Na D indices obtained by the use of the fitting functions are redder for all metallicities, Fe5709 is redder at Z = 0.03 and becomes bluer at Z = 0.01 and 0.004, and the other indices are bluer for all metallicities than the corresponding values measured directly from the synthetic spectra.

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