Can geocomputation save urban simulation? Throw some agents into the mixture, simmer and wait ...

There are indications that the current generation of simulation models in practical, operational uses has reached the limits of its usefulness under existing specifications. The relative stasis in operational urban modeling contrasts with simulation efforts in other disciplines, where techniques, theories, and ideas drawn from computation and complexity studies are revitalizing the ways in which we conceptualize, understand, and model real-world phenomena. Many of these concepts and methodologies are applicable to operational urban systems simulation. Indeed, in many cases, ideas from computation and complexity studies—often clustered under the collective term of geocomputation, as they apply to geography—are ideally suited to the simulation of urban dynamics. However, there exist several obstructions to their successful use in operational urban geographic simulation, particularly as regards the capacity of these methodologies to handle top-down dynamics in urban systems. This paper presents a framework for developing a hybrid model for urban geographic simulation and discusses some of the imposing barriers against innovation in this field. The framework infuses approaches derived from geocomputation and complexity with standard techniques that have been tried and tested in operational land-use and transport simulation. Macro-scale dynamics that operate from the topdown are handled by traditional land-use and transport models, while micro-scale dynamics that work from the bottom-up are delegated to agent-based models and cellular automata. The two methodologies are fused in a modular fashion using a system of feedback mechanisms. As a proof-of-concept exercise, a micro-model of residential location has been developed with a view to hybridization. The model mixes cellular automata and multi-agent approaches and is formulated so as to interface with meso-models at a higher scale

A new species of Pseudochalcura (Hymenoptera, Eucharitidae), with a review of antennal morphology from a phylogenetic perspective

Pseudochalcura alba Heraty & Heraty, sp. n. is described from Santiago del Estero and Catamarca provinces in northwestern Argentina. The male and female have long dorsal rami on all of the flagellomeres basal to the terminal segment, which is a unique feature within the genus and shared only with some species of Rhipipalloidea. Antennal modifications are compared across the Stilbula clade, of which all are parasitoids of Camponotini (Formicinae). A phylogenetic hypothesis for the group is proposed based on an analysis of 28S and 18S sequence data for 28 species. Ramose antennae are derived independently in both males and females across the clade, but with fully ramose female antennae restricted to the New World prolata group of Pseudochalcura and to some species of the Old World genus Rhipipalloidea. A sister group relationship between these genera is proposed based on both morphological and molecular data. Female antennae in other species of these genera, and other genera in the clade are at most dorsally lobate or serrate, but more commonly cylindrical. Monophyly of species of Obeza and Lophyrocera is supported and linked to a behavioral trait of ovi-position into fruits as opposed to flower heads or leaf buds. Within the Stilbula clade, a dichotomy between New and Old World taxa suggest relatively recent post-Miocene exchanges across the Northern Hemisphere.Fil: Heraty, John Michael. University of California; Estados UnidosFil: Heraty, Joanne M.. University of California; Estados UnidosFil: Torrens, Javier. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Secretaría de Industria y Minería. Servicio Geológico Minero Argentino. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones Científicas y Transferencia Tecnológica de La Rioja; Argentin

Palladium and Platinum Complexes of Bis(alkylthio)alkanes

Novel bis (alkylthio )alkanes containing fluorinated substituents in either the sulphur atoms or the bridge have been prepared by metathetical or photochemical reactions e. g. CF3S- + CH3SCH2CH2Br --> CH3SCH2CH2SCF3 + Br- 2CH3SH + CF3C=CH -hv→ CH3CH(CF3)CH2SCH3 Photolytic reactions of CH3SSCH3 and CH3SH are considered to proceed via CH3S. radicals. Interaction of fluorinated bis (alkylthio )alkanes with [PdCl4]2-or [PtCl4]2- afforded 44 new complexes with the general formula (RSR'Sr'')MX2, where R and R'' - CH3, CF3, C6F5; R' = CH2CH2, CH(CH3) CH(CH3) CF2CH2,CH(CF3)CH(CF3), CH(CF3)CH2; M- Pd, Pt and X= Cl, Br, I; but not all combinations were obtained. Ligands containing both hydrocarbon and fluorocarbon sulphur substituents, e. g. CH3SC2H4SCF3, form 1:1 and 2:1 complexes acting as bidentate or monodentate ligands respectively. In the last case only the CH3S grouping is coordinated and both cis and trans isomers were obtained. No reaction was found to take place between fluorinated sulphides, e. g. CH3SCF3, and either palladium(II) or platinum(II) salts. Differences in the observed chemical reactions of hydrocarbon and fluorocarbon sulphides and dithioethers towards Pd(II) and Pt(II) are discussed in relation to the sulphur-metal bond. X-ray studies of (CF3SCH(CH3) CH2SCF3)PtCl2 have shown that sulphur-platinum bond lengths are slightly shorter than in cis ((p-C6H4Cl)2S)2PtCl2, the most directly comparable structure known. The results have also revealed strong non bonded sulphur-chlorine interactions between pairs of centrosymmetrically related molecules. In solution, all five membered chelate ring complexes exhibit isomerism due to inversion of configuration at sulphur. The total number of stereoisomers depends also on the substituents in the bridge. Thus for compound containing BSCH2CH2SR, RSCH(R)CH2SR and RSCH(R)CH(R)SR ligands, 2, 4 and 6 isomers are possible. N. m. r. spectra of the anti isomers of compounds containing bis (perfluoro-alkylthio)alkanes e. g. (CF3SC2H4SCF3)PtCl2 show fluorine-fluorine coupling between fluorine atoms in different sulphur substituents. This coupling is rationalized in terms of a 'through space' mechanism. N. m. r. spectra of (CF3SC2H4SCF3)PtClBr confirm the proposed structural assignment. The isomeric structure of most platinum compounds have also been tentatively assigned based on n. m. r. parameters. The effect of variable concentration in the bromine substitution reaction involving (CH3SCF3)PtCl2 has been monitored by n. m. r. spectroscopy. Substitution takes place, preferentially trans to the CF3S grouping. Viariable temperature n. m. r. of (CF3SC2H4SCF3)PtCl2 shows that the coalescence temperature of this compound is higher than that found for the corresponding hydrocarbon analogue, probably due to the higher electronegativity and larger mass of the fluorinated substituents. Dynamic n. m. r. studies of (CH3SCH(CF3)CH(CF3)SCH3)PtI2 found two different intramolecular processes: at 183 K the bridge carbon-carbon bond rotation is sufficiently slow to detect the individual resonances arising from two diastereoisomers of a syn isomer. At high temperature the coalescence of resonances arising from anti and syn structures is discussed in terms of sulphur inversion taking place preferentially at single sulphur atoms. Platinum chemical shifts determined for several complexes have been found to be dependent on both the ligands present and the structure of the compounds. The values of d195 Pt for different halide complexes seem to follow additive rules. Values of platinum chemical shift for different stereoisomers of a given complex are qualitatively discussed in terms of intramolecular magnetic fields. Brief studies of reduction and ligand substitution reactions e. g. bis(cyclo-octa-1,5-diene)platinum(0) + CF3SC2H4SCF3, were carried out in an attempt to obtain zerovalent platinum complexes with sulphur containing ligands

Meaningful talk

In economics, the standard approach to language is that talk is cheap. Here, instead, language is a social convention that affects utility. Unless language is used in its ordinary sense, it cannot help to coordinate actions because there is no way of decoding it. This points to a unique informative equilibrium where words are used in their ordinary sense in natural language. Misrepresentation costs may eliminate uninformative, babbling, equilibria. More generally, meaningful talk provides a concrete mechanism through which consistent expectations are generated in Nash equilibria

Meaningful Talk

This paper develops a semiotic-inferential model of verbal communication for incomplete information games: a language is seen as a set of conventional signs that point to types, and the credibility of a message depends on the strategic context. Formally, there is an encoding-decoding step where the receiver can understand the sender's message if and only if a common language is used, and an inferential step where the receiver may either trust the message's literal meaning or disregard it when updating priors. The epistemic requirement that information be transmitted through the literal meaning of the message uttered leads to an equilibrium concept distinct from a Perfect Bayesian Equilibrium, ruling out informative equilibria where language is not used in its ordinary sense. The paper also proposes a refinement by which the sender selects among equilibria if all sender types are willing to play the same equilibrium