Unary FA-presentable semigroups

Automatic presentations, also called FA-presentations, were introduced to extend nite model theory to innite structures whilst retaining the solubility of interesting decision problems. A particular focus of research has been the classication of those structures of some species that admit automatic presentations. Whilst some successes have been obtained, this appears to be a dicult problem in general. A restricted problem, also of signicant interest, is to ask this question for unary automatic presentations: auto-matic presentations over a one-letter alphabet. This paper studies unary FA-presentable semigroups. We prove the following: Every unary FA-presentable structure admits an injective unary automatic presentation where the language of representatives consists of every word over a one-letter alphabet. Unary FA-presentable semigroups are locally nite, but non-nitely generated unary FA-presentable semigroups may be innite. Every unary FA-presentable semigroup satises some Burnside identity.We describe the Green's relations in unary FA-presentable semigroups. We investigate the relationship between the class of unary FA-presentable semigroups and various semigroup constructions. A classication is given of the unary FA-presentable completely simple semigroups.PostprintPeer reviewe

⁸⁷Sr/⁸⁶Sr chemostratigraphy of Neoproterozoic Dalradian limestones of Scotland and Ireland: constraints on depositional ages and time scales

New calcite <sup>87</sup>Sr/<sup>86</sup>Sr data for 47 limestones from the metamorphosed and deformed Neoproterozoic-Cambrian Dalradian Supergroup of Scotland and Ireland are used to identify secular trends in seawater <sup>87</sup>Sr/<sup>86</sup>Sr through the Dalradian succession and to constrain its depositional age. Dalradian limestones commonly have Sr greater than 1000 ppm, indicating primary aragonite and marine diagenesis. Low Mn, Mn/Sr less than 0.6, ë<sup>18</sup>O and trace element data indicate that many <sup>87</sup>Sr/<sup>86</sup>Sr ratios are unaltered since diagenesis despite greenschist- to amphibolite-facies metamorphism, consistent with the documented behaviour of Sr and O during metamorphic fluid-rock interaction. Thus, the <sup>87</sup>Sr/<sup>86</sup>Sr data are interpreted largely to reflect <sup>87</sup>Sr/<sup>86</sup>Sr of coeval seawater. Currently available data show that Neoproterozoic seawater <sup>87</sup>Sr/<sup>86</sup>Sr rose from c. 0.7052 at 850-900 Ma to c. 0.7085 or higher in the latest Neoproterozoic. Temporal changes at c. 800 Ma and c . 600 Ma bracket the range in <sup>87</sup>Sr/<sup>86</sup>Sr values of calcite in Grampian. Appin and lowest Argyll Group (c.0.7064-0.7072) and middle and uppermost Argyll Group (c. 0.7082-0.7095) limestones, consistent with a rise in seawater <sup>87</sup>Sr/<sup>86</sup>Sr around 600 Ma. <sup>87</sup>Sr/<sup>86</sup>Sr data are consistent with the sedimentary affinity of the Islay Subgroup with the underlying Appin Group, and with a possible time interval between deposition of Islay and Easdale Subgroup rocks. They indicate that the Dalradian, as a whole, is younger than c. 800 Ma

Csk is an important negative regulator of phagocyte responsiveness in vivo: characterisation of myeloid cell-specific Csk deficiency in mice by conditional mutagenesis (Cre/loxP).

Whilst the recruitment of phagocytic leukocytes is fundamental to the innate response against pathogenic infection, the inappropriate mobilisation of their cytotoxic potential can also lead to fatal tissue injury. To determine the contribution of Csk, a negative regulator of Src family kinases, to the regulation of phagocyte recruitment and activation in vivo, mice lacking Csk in the myeloid lineage were generated using conditional mutagenesis (cre/loxP). This Csk deficiency resulted in acute multifocal inflammation in skin and lung, accompanied by extramedullary haematopoiesis in the spleen and liver, and increased myelopoiesis in bone marrow. Animals were protected from the disease in a microbiologically controlled environment, but remained hypersensitive to LPS-induced shock. Csk-deficient granulocytes showed enhanced spontaneous and ligand-induced degranulation accompanied by hyperinduction of integrins. Hyperresponsiveness was associated with hyperadhesion and impaired migratory responses in vitro. Biochemical studies revealed spontaneous accumulation of tyrosine-phosphorylated proteins, including hyperphosphorylation of key signalling proteins including Syk and paxillin. These data support a breakdown of the activation threshold set by Csk. Thus, Csk is critical in preventing premature granulocyte recruitment through enforcing the requirement for ligand engagement while supporting the migratory capacity of activated cells through negative regulation of cell adhesion. To address the incomplete Cre mediated deletion of floxed genes in vivo, a genetic approach to elevate Cre recombinase gene expression was developed. Whilst manipulation of regulatory elements including promoter, enhancer, and untranslated regions has yielded enhanced and sustained expression in vitro, this has been difficult to achieve in vivo. Here, it is reported that construction of artificial exons through insertion of short heterologous intron sequences into the open reading frames of the Cre recombinase and enhanced green fluorescent protein results in functional expression accompanied by a 30-fold increase in transcription levels in vitro. Furthermore, green fluorescence levels were enhanced five-fold in cell lines and enhanced considerably in the rat brain after transduction with a herpes simplex virus-based vector. These data define a method of improving both the level and duration of recombinant gene expression, in addition to and independently of surrounding regulatory elements. Significantly, the method should help to increase Cre recombinase expression from weak or transiently expressed promoters thus overcoming an important limitation of Cre/loxP technology incomplete deletion. Furthermore, this method may also be applicable in gene therapy to obtain sustained and effective expression of recombinant proteins in vivo

A visual conflict hypothesis for global-local visual deficits in Williams Syndrome: simulations and data

Individuals with Williams Syndrome demonstrate impairments in visuospatial cognition. This has been ascribed to a local processing bias. More specifically, it has been proposed that the deficit arises from a problem in disengaging attention from local features. We present preliminary data from an integrated empirical and computational exploration of this phenomenon. Using a connectionist model, we first clarify and formalize the proposal that visuospatial deficits arise from an inability to locally disengage. We then introduce two empirical studies using Navon-style stimuli. The first explored sensitivity to local vs. global features in a perception task, evaluating the effect of a manipulation that raised the salience of global organization. Thirteen children with WS exhibited the same sensitivity to this manipulation as CA-matched controls, suggesting no local bias in perception. The second study focused on image reproduction and demonstrated that in contrast to controls, the children with WS were distracted in their drawings by having the target in front of them rather than drawing from memory. We discuss the results in terms of an inability to disengage during the planning stage of reproduction due to over-focusing on local elements of the current visual stimulus

Using artificial neural networks to predict future dryland responses to human and climate disturbances

Land degradation and sediment remobilisation in dryland environments is considered to be a significant global environmental problem. Given the potential for currently stabilised dune systems to reactivate under climate change and increased anthropogenic pressures, identifying the role of external disturbances in driving geomorphic response is vitally important. We developed a novel approach, using artificial neural networks (ANNs) applied to time series of historical reactivation-deposition events from the Nebraska Sandhills, to determine the relationship between historic periods of sand deposition in semi-arid grasslands and external climatic conditions, land use pressures and wildfire occurrence. We show that both vegetation growth and sediment re-deposition episodes can be accurately estimated. Sensitivity testing of individual factors shows that localised forcings (overgrazing and wildfire) have a statistically significant impact when the climate is held at present-day conditions. However, the dominant effect is climate-induced drought. Our approach has great potential for estimating future landscape sensitivity to climate and land use scenarios across a wide range of potentially fragile dryland environments

Techno-economic Evaluation Methodology and Preliminary Comparison of an Amine-based and Advanced Solid Sorbent-based CO2 Capture Process for NGCC Power Plants

AbstractThe post combustion capture process using the traditional amine based solvent absorption process is a very mature technology that suffers from a high energy penalty being taken on the power plant and requires significant capital investment that causes us a high increase in the cost of electricity. An advanced solid-based adsorption is discussed in this work as well as a techno-economic evaluation methodology in order to compare the advantages of this novel process to the conventional process. Some indications of the expected technical and economic benefits of the process are also discussed

On the length of chains of proper subgroups covering a topological group

We prove that if an ultrafilter L is not coherent to a Q-point, then each analytic non-sigma-bounded topological group G admits an increasing chain <G_a : a of its proper subgroups such that: (i) U_{a in b(L)} G_a=G; and $(ii)$ For every sigma-bounded subgroup H of G there exists a such that H is a subset of G_a. In case of the group Sym(w) of all permutations of w with the topology inherited from w^w this improves upon earlier results of S. Thomas

The development of metaphorical language comprehension in typical development and in Williams syndrome

The domain of figurative language comprehension was used to probe the developmental relation between language and cognition in typically developing individuals and individuals with Williams syndrome. Extending the work of Vosniadou and Ortony, the emergence of nonliteral similarity and category knowledge was investigated in 117 typically developing children between 4 and 12 years of age, 19 typically developing adults, 15 children with Williams syndrome between 5 and 12 years of age, and 8 adults with Williams syndrome. Participants were required to complete similarity and categorization statements by selecting one of two words (e.g., either “The sun is like ___” or “The sun is the same kind of thing as ___”) with word pairs formed from items that were literally, perceptually, or functionally similar to the target word or else anomalous (e.g., moon, orange, oven, or chair, respectively). Results indicated that individuals with Williams syndrome may access different, less abstract knowledge in figurative language comparisons despite the relatively strong verbal abilities found in this disorder