Local and semilocal density functional computations for crystals of 1-alkyl-3-methyl-imidazolium salts

The accuracy and reliability of popular density functional approximations for the compounds giving origin to room temperature ionic liquids have been assessed by computing the T=0 K crystal structure of several 1-alkyl-3-methyl-imidazolium salts. Two prototypical exchange-correlation approximations have been considered, i.e., the local density approximation (LDA) and one gradient corrected scheme [PBE-GGA, Phys. Rev. Lett. 77, 3865 (1996)]. Comparison with low-temperature x-ray diffraction data shows that the equilibrium volume predicted by either approximations is affected by large errors, nearly equal in magnitude (~10%), and of opposite sign. In both cases the error can be traced to a poor description of the intermolecular interactions, while the intramolecular structure is fairly well reproduced by LDA and PBE-GGA. The PBE-GGA optimization of atomic positions within the experimental unit cell provides results in good agreement with the x-ray structure. The correct system volume can also be restored by supplementing PBE-GGA with empirical dispersion terms reproducing the r-6 attractive tail of the van der Waals interactions.

IntCal04 terrestrial radiocarbon age calibration, 0-26 cal kyr BP

A new calibration curve for the conversion of radiocarbon ages to calibrated (cal) ages has been constructed and internationally ratified to replace IntCal98, which extended from 0-24 cal kyr BP (Before Present, 0 cal BP = AD 1950). The new calibration data set for terrestrial samples extends from 0-26 cal kyr BP, but with much higher resolution beyond 11.4 cal kyr BP than IntCal98. Dendrochronologically-dated tree-ring samples cover the period from 0-12.4 cal kyr BP. Beyond the end of the tree rings, data from marine records (corals and foraminifera) are converted to the atmospheric equivalent with a site-specific marine reservoir correction to provide terrestrial calibration from 12.4-26.0 cal kyr BP. A substantial enhancement relative to IntCal98 is the introduction of a coherent statistical approach based on a random walk model, which takes into account the uncertainty in both the calendar age and the (super 14) C age to calculate the underlying calibration curve (Buck and Blackwell, this issue). The tree-ring data sets, sources of uncertainty, and regional offsets are discussed here. The marine data sets and calibration curve for marine samples from the surface mixed layer (Marine04) are discussed in brief, but details are presented in Hughen et al. (this issue a). We do not make a recommendation for calibration beyond 26 cal kyr BP at this time; however, potential calibration data sets are compared in another paper (van der Plicht et al., this issue).

Video games in the classrooms: implications of a disruptive innovation to develop the Multiple Intelligences

The present study aims to identify the framework of personal, organizational and technical variables that contribute to the viability and successful of innovative educational practices with video games within the school context to enhance the multiple intelligences. For this purpose, advantage was taken on the information previously collected through a questionnaire about the views, thoughts and experiences of a group of teachers of childhood and primary education (N=25) who voluntarily participated in a blended training activity from Center of Teachers (CEFIRE) of Valencia, around a community of practice aimed at promoting and advising projects for implementing educational video games in the classroom. The mixed methodology adopted has allowed the following: a) describe the relationship between their degree of development and daily use made of ICT in the classroom, their level of familiarity with video games,  their previous experience to integrate them for educational purposes..., and their participation in projects that focus on game-based learning; b) conduct content analysis of the opinions and thoughts expressed in a forum for teachers on innovation on and methodological strategies adopted reflected in a virtual board; and c) develop a SWOT analysis: Strengths, Weaknesses, Opportunities and Threats inherent in the implementation of experience with video games in the classroom. Among the conclusions, it is highlighted that, even though most did not have specific training or enough technological resources and the planning and implementation of innovation required them a great investment of time, their personal interest, the support given by members of the online community of practice, helped to encourage their activity, along with receptivity, positive attitude and high motivation of students with the experience. These aspects have been crucial to promote successful innovative practices with video games.

On the origin of the forward peak and backward oscillations in the F + H2(v = 0) to HF(v' = 2) + H reaction

We present a semiclassical complex angular momentum (CAM) analysis of the forward scattering peak which occurs at a translational collision energy around 32 meV in the quantum mechanical calculations for the F + H2(v = 0, j = 0) ? HF(v' = 2, j' = 0) + H reaction on the Stark–Werner potential energy surface. The semiclassical CAM theory is modified to cover the forward and backward scattering angles. The peak is shown to result from constructive/destructive interference of the two Regge states associated with two resonances, one in the transition state region and the other in the exit channel van der Waals well. In addition, we demonstrate that the oscillations in the energy dependence of the backward differential cross section are caused by the interference between the direct backward scattering and the decay of the two resonance complexes returning to the backward direction after one full rotation.

Feeding on micro-algae in the invasive Ponto-Caspian amphipod Dikerogammarus villosus (Sowinsky, 1894)

Feeding on micro-algae is shown in the invasive Ponto-Caspian amphipod Dikerogammarus villosus. Compared with controls, males, females and juveniles of this species significantly reduced the concentration in suspension of unicellular micro-algae. Juveniles had higher concentrations of algae in the cardiac gut than adults. The presence of these algae in the mid- and hindgut was also recorded. This feeding behaviour was filmed and the mechanisms involved are described and discussed. We comment on the use of the Functional Feeding Group (FFG) concept to classify feeding in amphipods. The role of being a feeding-generalist in aiding the invasion process is also discussed.