Radiolysis of ammonia-containing ices by energetic, heavy and highly charged ions inside dense astrophysical environments

Deeply inside dense molecular clouds and protostellar disks, the interstellar ices are protected from stellar energetic UV photons. However, X-rays and energetic cosmic rays can penetrate inside these regions triggering chemical reactions, molecular dissociation and evaporation processes. We present experimental studies on the interaction of heavy, highly charged and energetic ions (46 MeV Ni^13+) with ammonia-containing ices in an attempt to simulate the physical chemistry induced by heavy ion cosmic rays inside dense astrophysical environments. The measurements were performed inside a high vacuum chamber coupled to the heavy ion accelerator GANIL (Grand Accelerateur National d'Ions Lourds) in Caen, France.\textit{In-situ} analysis is performed by a Fourier transform infrared spectrometer (FTIR) at different fluences. The averaged values for the dissociation cross section of water, ammonia and carbon monoxide due to heavy cosmic ray ion analogs are ~2x10^{-13}, 1.4x10^{-13} and 1.9x10^{-13} cm$^2$, respectively. In the presence of a typical heavy cosmic ray field, the estimated half life for the studied species is 2-3x10^6 years. The ice compaction (micropore collapse) due to heavy cosmic rays seems to be at least 3 orders of magnitude higher than the one promoted by (0.8 MeV) protons . In the case of the irradiated H2O:NH3:CO ice, the infrared spectrum at room temperature reveals five bands that were tentatively assigned to vibration modes of the zwitterionic glycine (+NH3CH2COO-).Comment: Accepted to be published in Astronomy and Astrophysics; Number of pages: 12; Number of Figures: 7; Number of Tables:

The great good place : coworking como espaço para aprender design uma framework exploratória

Abstract : In this paper we explore a conceptual framework based on three lines of thinking/work from Patrick Cohendet (Underground/Middleground/Upperground), Ray Oldenburg (The Great Good Place), and Fred Garneti (Heutagogy or Self-determined Learning). To demonstrate the relevance and feasibility of our proposed concept, we review the key factors and definitions of these authors and their work. Although not a theoretical framework, the present paper aims to help us map a part of our research work within the context of the Doctoral Programme in Design at IADE / Universidade Europeia, which triangulates Coworking, Design Learning, and Heutagogy or selfdetermined modes of learning. Ultimately, the aim is to generate new evidence on how such a model of Coworking Design Learning can benefit and betier suit contemporary Design learners.Neste artigo, exploramos uma estrutura conceptual baseada em três linhas de pensamento dos autores Patrick Cohendet (Underground / Middleground / Upperground), Ray Oldenburg (The Great Good Place) e Fred Garneti (Heutagogy or Self-determined Learning). Para demonstrar a relevância e a viabilidade da nossa proposta conceptual, revisitamos os principais fatores e definições destes autores e dos seus trabalhos. Embora não constitua uma framework teórica, o presente trabalho tem como objetivo ajudar a mapear parte do nosso trabalho de pesquisa no contexto do Programa de Doutoramento em Design do IADE / Universidade Europeia, que triangula Coworking, Aprendizagem de Design e Heutagogia ou modos autodeterminados de aprendizagem. Em última instância, o objetivo é tentar produzir novas evidências sobre como um modelo de aprendizagem de Design baseado em espaços de Coworking pode beneficiar e adequar-se melhor aos actuais alunos de Design.info:eu-repo/semantics/publishedVersio

A Method to Tackle First Order Differential Equations with Liouvillian Functions in the Solution - II

We present a semi-decision procedure to tackle first order differential equations, with Liouvillian functions in the solution (LFOODEs). As in the case of the Prelle-Singer procedure, this method is based on the knowledge of the integrating factor structure.Comment: 11 pages, late

Evolutionary and Ecological Trees and Networks

Evolutionary relationships between species are usually represented in phylogenies, i.e. evolutionary trees, which are a type of networks. The terminal nodes of these trees represent species, which are made of individuals and populations among which gene flow occurs. This flow can also be represented as a network. In this paper we briefly show some properties of these complex networks of evolutionary and ecological relationships. First, we characterize large scale evolutionary relationships in the Tree of Life by a degree distribution. Second, we represent genetic relationships between individuals of a Mediterranean marine plant, Posidonia oceanica, in terms of a Minimum Spanning Tree. Finally, relationships among plant shoots inside populations are represented as networks of genetic similarity.Comment: 6 pages, 5 figures. To appear in Proceedings of the Medyfinol06 Conferenc

The Hyperbolic Forest Owner

This paper examines the implications of quasi-hyperbolic inter-temporal preferences to the Faustman model. The use of decreasing discount rates leads to dynamically inconsistent behavior. To solve this problem a two-stages optimization decision model is developed. The resulting actual cutting time will be anticipated compared to the Faustman optimal cutting time. If, alternatively, the equivalent constant rate of discount is the empirically observed discount rate, then the optimal cutting time is the same, but the present value of profits for the hyperbolic forest owner is always higher than the one resulting from the equivalent constant discount rate. All these results apply to both the single and the multiple rotation problems.Hyperbolic discounting; time preference; dynamic inconsistency; Faustman model; optimal rotation