Modelling line emission of deuterated H_3^+ from prestellar cores

Context: The depletion of heavy elements in cold cores of interstellar molecular clouds can lead to a situation where deuterated forms of H_3^+ are the most useful spectroscopic probes of the physical conditions. Aims: The aim is to predict the observability of the rotational lines of H_2D^+ and D_2H^+ from prestellar cores. Methods: Recently derived rate coefficients for the H_3^+ + H_2 isotopic system were applied to the "complete depletion" reaction scheme to calculate abundance profiles in hydrostatic core models. The ground-state lines of H_2D^+(o) (372 GHz) and D_2H^+(p) (692 GHz) arising from these cores were simulated. The excitation of the rotational levels of these molecules was approximated by using the state-to-state coefficients for collisions with H_2. We also predicted line profiles from cores with a power-law density distribution advocated in some previous studies. Results: The new rate coefficients introduce some changes to the complete depletion model, but do not alter the general tendencies. One of the modifications with respect to the previous results is the increase of the D_3^+ abundance at the cost of other isotopologues. Furthermore, the present model predicts a lower H_2D^+ (o/p) ratio, and a slightly higher D_2H^+ (p/o) ratio in very cold, dense cores, as compared with previous modelling results. These nuclear spin ratios affect the detectability of the submm lines of H_2D^+(o) and D_2H^+(p). The previously detected H_2D^+ and D_2H^+ lines towards the core I16293E, and the H_2D^+ line observed towards Oph D can be reproduced using the present excitation model and the physical models suggested in the original papers.Comment: 10 pages, 11 Figures; ver2: updated some of the Figures, added some references, added an entry to acknowledgement

The Linking of Collective Decisions and Efficiency

For groups that must make several decisions of similar form, we define a simple and general mechanism that is designed to promote social efficiency. The mechanism links the various decisions by forcing agents to budget their representations of preferences so that the frequency of preferences across problems conforms to the underlying distribution of preferences. We show that as the mechanism operates over a growing number decisions, the welfare costs of incentive constraints completely disappear. In addition, as the number of decisions being linked grows, a truthful strategy is increasingly successful and secures the efficient utility level for an agent.linking decisions, mechanism design, incentives, incentive compatibility, bundling

New Firm Growth: Exploring Processes and Paths

This paper provides a new methodology for the diachronic study of new firm growth, theoretically grounded in the work of Penrose (1995). We show that a model of firm growth as an unfolding process makes possible draw simple, measurable inferences from firm level to aggregate evidence on growth paths of new firms, expressed as propositions. Metrics on growth paths of new firms in three longitudinal samples of new firms are examined for evidence at the aggregate level consistent with the dynamic model. Dynamic processes in the early development of young firms result in variations in the timing, magnitude, duration and rate of change of growth as between firms and in the same firm over time. The conceptual and methodological framework in this paper provides a basis for future research aimed at explaining the development of new firms.entrepreneurship;Penrose;growth paths;new firm growth;resource-based perspective

Un problema de estética en el "Libro de Buen Amor" : la heterogeneidad lingüística

Los estudios tanto lingüísticos como literarios del Libro de \ud buen amor han resaltado la compleja variedad de registros lingüísticos que el \ud autor utiliza: lenguaje coloquial junto al erudito, refranes junto a sentencias, \ud mezcla de jergas y hasta versos en latín o árabe. En este arículo se intenta \ud estudiar este aspecto de la obra ruiciana desde el punto de vista de su funcionalidad estética. Así se puede observar que esos diversos registros no son \ud independientes de los diferentes tipos de piezas que incorpora Juan Ruiz a su \ud libro, pues el autor no sólo reproduce modelos literarios, sino también el tipo \ud de lengua que estos utilizan.So the linguistic studies as the literary also about the Libro de \ud buen amor have highlighted ther complex varyety of linguistic registers the \ud author uses : colloquial language next to erudite one, proverbs next to \ud maxims, a mixture of jargoons and even latin or arab verses. In the present article we intend to study this aspect of the book from the point of viwe of \ud his esthetic function. So it is possible to observe that those various registers \ud are not independent from the diverse kind of texts which the author incorpórate in his book, as the author reproduce not only hterary models, but also \ud the kind of language that those employ

El surgimiento de un pensamiento económico en Castilla (Historia de una idea desde Pedro Alfonso hasta Fray Juan García de Castrojeriz)

Sin resume

A Self Consistent Reaction Field Study on Electrostatic Isopotential Maps

The influence of a self consistent reaction field on the charge distribution of molecular systems is studied. Electrostatic isopotential maps are used to discuss the qualitative and quantitative aspects of such an influence