Evidence of a collision between the Yucatán Block and Mexico in the Miocene

We present the evidence for an anomalous southwest-dipping slab in southern Mexico. The main evidence comes from a clear receiver function image along a seismic line across the Isthmus of Tehuantepec and is also supported by a previous global tomographic model. The slab dips at 35°, is approximately 250 km in length and appears to truncate the Cocos slab at about 120 km depth. We hypothesize that the slab was created by subduction of oceanic lithosphere prior to the collision of the Yucatán Block with Mexico at approximately 12 Ma. This scenario would explain the Chiapas Fold and Thrust Belt as the product of this collision, and its age constrains the date of the event to be in the Miocene

Free energy barrier for molecular motions in bistable [2]rotaxane molecular electronic devices

Donor−acceptor binding of the π-electron-poor cyclophane cyclobis(paraquat-p-phenylene) (CBPQT^(4+)) with the π-electron-rich tetrathiafulvalene (TTF) and 1,5-dioxynaphthalene (DNP) stations provides the basis for electrochemically switchable, bistable [2]rotaxanes, which have been incorporated and operated within solid-state devices to form ultradense memory circuits (ChemPhysChem 2002, 3, 519−525; Nature 2007, 445, 414−417) and nanoelectromechanical systems. The rate of CBPQT^(4+) shuttling at each oxidation state of the [2]rotaxane dictates critical write-and-retention time parameters within the devices, which can be tuned through chemical synthesis. To validate how well computational chemistry methods can estimate these rates for use in designing new devices, we used molecular dynamics simulations to calculate the free energy barrier for the shuttling of the CBPQT^4+ ring between the TTF and the DNP. The approach used here was to calculate the potential of mean force along the switching pathway, from which we calculated free energy barriers. These calculations find a turn-on time after the rotaxane is doubly oxidized of ~10^9−7) s (suggesting that the much longer experimental turn-on time is determined by the time scale of oxidization). The return barrier from the DNP to the TTF leads to a predicted lifetime of 2.1 s, which is compatible with experiments

Estimating Technical Efficiency of Australian Dairy Farms Using Alternative Frontier Methodologies

In this paper we estimate and examine technical efficiency for a cross-section of Australian dairy farms using various frontier methodologies; Bayesian and Classical stochastic frontiers, and Data Envelopment Analysis. Our results indicate technical inefficiency is present in the sample data. We also identify statistical differences between the point estimates of technical efficiency generated by the various methodologies. However, the rank of farm level technical efficiency is statistically invariant to the estimation technique employed. Finally, when we compare confidence/credible intervals of technical efficiency we find significant overlap for many of the farms’ intervals for all frontier methods employed. Our results indicate that the choice of estimation methodology may matter, but the explanatory power of all frontier methods is significantly weaker when we examine interval estimate of technical efficiency

Motivation and Behaviour Change in Parkrun Participants in the Western Cape Province, South Africa

Mass participation events are promoted in South Africa as a positive public health initiative. Parkrun has grown to be one of the most popular. The present study identifies the motives of residents in the Western Cape Province to join parkrun and how their involvement influences future physical activity levels. Participants (N = 1787) completed a survey consisting of demographic history, parkrun participation history, motivations for participation, and physical activity-related behaviour changes associated with parkrun participation. The majority of participants were female (n = 952) and over 50 years of age (median = 50; IQR = 38–59). Along with health-related benefits, the provision of a safe and organised event was reported as a key motive to participate. The social connectedness developed by parkrun encouraged continued participation and promoted uptake of more physical activity. Close to half the participants reported increases in physical activity levels after joining parkrun, which demonstrates the benefit obtained from participation in structured mass participation events. With the large diversity in socioeconomic status in South Africa related to physical activity levels, parkrun provides a protected and engaging environment that provides opportunity for increased physical activity and potentially reducing the burden on the healthcare system

Explaining cross-cultural pragmatic findings: moving from politeness maxims to sociopragmatic interactional principles (SIPs)

This paper focuses on how culture can be treated as an explanatory variable in cross-cultural pragmatic studies. It starts with a review of pragmatic maxims [Grice, H. Paul, 1989. Logic and Conversation. William James Lectures, 1967. (Reprinted in Grice, H.P. (Ed.), Studies in the Way of Words, pp. 22–40); Leech, Geoffrey N., 1983. Principles of Pragmatics. London: Longman; Journal of Pragmatics 14 (1990)237], discussing the strengths and weaknesses of the concept. It then presents the findings from a British-Chinese replication of Kim's [Human Communication Research 21(1996)128] cross-cultural study of conversational constraints, and argues that the notion of maxims should be reconceptualised as sociopragmatic interactional principles (SIPs). The notion of SIPs is defined and explained, referring to the sociopragmatic-pragmalinguistic distinction [Leech, Geoffrey N., 1983. Principles of Pragmatics. London: Longman; Applied Linguistics 4(1983)91] and other cross-cultural pragmatic approaches [House, Julianne, 2000. Understanding misunderstanding: a pragmatic-discourse approach to analyzing mismanaged rapport in talk across cultures. In: Spencer-Oatey, H. (Ed.), Culturally Speaking. Managing Rapport through Talk across Cultures. Continuum, London; 145–164; Journal of Pragmatics 9 (1985)145]. SIPs are also discussed in relation to Brown and Levinson's [Brown, Penelope, Levinson, Stephen C., 1987. Politeness. Some Universals in Language Usage. CUP, Cambridge (Originally published ad ‘Universals in language usage: politeness phenomenon’ In: Goody, E. (1987), Questions and Politeness: Strategies in Social Interaction. CUP, New York.)] perspectives on the impact of culture on language use. The paper ends with a call for more research to establish on an empirical basis the types of interactional principles that exist, and their interrelationships

A model for principals' STEM leadership capability

In this paper we develop a model for the capabilities required by principals for effective Science, Technology, Engineering and Mathematics (STEM) leadership. The model underpinned a large national cross-sectional research and development project across Australian states in both primary and secondary schools. This model is developed via synthesis of research literature across leadership and STEM education. The model consists of five dimensions of principals' STEM capability: (1) STEM discipline-specific and integrated knowledge and practices; (2) contexts; (3) dispositions; (4) tools; and (5) critical orientation. These dimensions represent distinct, but interrelated, capacities required by principals to establish and maintain positive STEM learning cultures within schools. Elaborations have been provided, in the form of capabilities, for each of these dimensions. The model has the potential for shaping principals' STEM leadership development trajectories and structuring targeted professional learning programmes for principals, teachers and other members of the school community

Graduate String Quartet: Taik-Ki Kim, Violin; Kathleen Fraser, Viola; Joonho Kim, Violin; Kyung-Jin Lee, Cello; December 16, 1972

Centennial East Recital HallThursday EveningDecember 16, 19718:15 p.m