Language understanding is grounded in experiential simulations: a response to Weiskopf

Several disciplines within the cognitive sciences have advanced the idea that people comprehend the actions of others, including the linguistic meanings they communicate, through embodied simulations where they imaginatively recreate the actions they observe or hear about. This claim has important consequences for theories of mind and meaning, such as that people’s use and interpretation of language emerges as a kind of bodily activity that is an essential part of ordinary cognition. Daniel Weiskopf presents several arguments against the idea that experiential simulations play a major role in immediate language use and meaning. We offer several rebuttals to Weiskopf, in which we critique his interpretation of simulation theory, present additional psycholinguistic evidence supportive of the simulation perspective, and suggest that a more traditional theory of linguistic meaning and processing has little psychological and empirical validity.     

Possible solar origin of the 1,470-year glacial climate cycle demonstrated in a coupled model

Many palaeoclimate records from the North Atlantic region show a pattern of rapid climate oscillations, the so-called Dansgaard-Oeschger events, with a quasi-periodicity of approximately 1,470 years for the late glacial period. Various hypotheses have been suggested to explain these rapid temperature shifts, including internal oscillations in the climate system and external forcing, possibly from the Sun. But whereas pronounced solar cycles of approximately 87 and approximately 210 years are well known, a approximately 1,470-year solar cycle has not been detected. Here we show that an intermediate-complexity climate model with glacial climate conditions simulates rapid climate shifts similar to the Dansgaard-Oeschger events with a spacing of 1,470 years when forced by periodic freshwater input into the North Atlantic Ocean in cycles of approximately 87 and approximately 210 years. We attribute the robust 1,470-year response time to the superposition of the two shorter cycles, together with strongly nonlinear dynamics and the long characteristic timescale of the thermohaline circulation. For Holocene conditions, similar events do not occur. We conclude that the glacial 1,470-year climate cycles could have been triggered by solar forcing despite the absence of a 1,470-year solar cycle.     

Break—even Analyses for Random production and Demand Processes

Break-even analyses are often used as controlling instruments. Typically, they are applied to support decision processes or to gain information for the control of profits and sales. Firstly, the study gives an overview of the basic accounting systems. Secondly, the study shows possible ways of performing breakeven analyses for a single-stage, make-to-order production in the case of random production and demand structures. To model these structures, queueing systems are employed. As a general result, we see that break-even analyses must always be performed taking into account an existing planning system. Under practical aspects, GI/G/1 systems turn out to map complex real situations realistically. From the examples given it can be concluded that one achieves different results compared with using a deterministic model even in the case of a simple, random effects approach. In particular it is shown that stochastic modelling in general is helpful in avoiding incorrect decisions.     

In situ nick-translation distinguishes between active and inactive X chromosomes

Template-active regions of chromatin are structurally distinct from nontranscribing segments of the genome. Recently, it was suggested that the conformation of active genes which renders them sensitive to DNase I may be maintained even in fixed mitotic chromosomes. We have developed a technique of mitotic cell fixation and DNase I-directed nick-translation which distinguishes between active and inactive X chromosomes. We report here that Gerbillus gerbillus (rodent) female cells contain easily identified composite X chromosomes each of which includes the original X chromosome flanked by two characteristic autosomal segments. After nick-translation the active X chromosome in each cell is labelled specifically in both the autosomal and X-chromosomal regions. The inactive X chromosome is labelled only in the autosomal regions and in a small early replicating band within the late replicating 'original X' chromosome. Our technique opens the possibility of following the kinetics of X-chromosome inactivation and reactivation during embryogenesis, studying active genes in the inactive X chromosome and mapping tissue-specific gene clusters.     

Drosophila odorant receptors are both ligand-gated and cyclic-nucleotide-activated cation channels

From worm to man, many odorant signals are perceived by the binding of volatile ligands to odorant receptors that belong to the G-protein-coupled receptor (GPCR) family. They couple to heterotrimeric G-proteins, most of which induce cAMP production. This second messenger then activates cyclic-nucleotide-gated ion channels to depolarize the olfactory receptor neuron, thus providing a signal for further neuronal processing. Recent findings, however, have challenged this concept of odorant signal transduction in insects, because their odorant receptors, which lack any sequence similarity to other GPCRs, are composed of conventional odorant receptors (for example, Or22a), dimerized with a ubiquitously expressed chaperone protein, such as Or83b in Drosophila. Or83b has a structure akin to GPCRs, but has an inverted orientation in the plasma membrane. However, G proteins are expressed in insect olfactory receptor neurons, and olfactory perception is modified by mutations affecting the cAMP transduction pathway. Here we show that application of odorants to mammalian cells co-expressing Or22a and Or83b results in non-selective cation currents activated by means of an ionotropic and a metabotropic pathway, and a subsequent increase in the intracellular Ca(2+) concentration. Expression of Or83b alone leads to functional ion channels not directly responding to odorants, but being directly activated by intracellular cAMP or cGMP. Insect odorant receptors thus form ligand-gated channels as well as complexes of odorant-sensing units and cyclic-nucleotide-activated non-selective cation channels. Thereby, they provide rapid and transient as well as sensitive and prolonged odorant signalling.