PyNeb: a new tool for analyzing emission lines. I. Code description and validation of results

Analysis of emission lines in gaseous nebulae yields direct measures of physical conditions and chemical abundances and is the cornerstone of nebular astrophysics. Although the physical problem is conceptually simple, its practical complexity can be overwhelming since the amount of data to be analyzed steadily increases; furthermore, results depend crucially on the input atomic data, whose determination also improves each year. To address these challenges we created PyNeb, an innovative code for analyzing emission lines. PyNeb computes physical conditions and ionic and elemental abundances, and produces both theoretical and observational diagnostic plots. It is designed to be portable, modular, and largely customizable in aspects such as the atomic data used, the format of the observational data to be analyzed, and the graphical output. It gives full access to the intermediate quantities of the calculation, making it possible to write scripts tailored to the specific type of analysis one wants to carry out. In the case of collisionally excited lines, PyNeb works by solving the equilibrium equations for an n-level atom; in the case of recombination lines, it works by interpolation in emissivity tables. The code offers a choice of extinction laws and ionization correction factors, which can be complemented by user-provided recipes. It is entirely written in the python programming language and uses standard python libraries. It is fully vectorized, making it apt for analyzing huge amounts of data. The code is stable and has been benchmarked against IRAF/NEBULAR. It is public, fully documented, and has already been satisfactorily used in a number of published papers.Comment: 17 pages, 12 figures. Accepted for publication in Astronomy & Astrophysics. Typos and reference list corrected in this versio

Longevity risks and capital markets: The 2010-2011 update

This Special Issue of Geneva Papers on Risk and Insurance - Issues and Practice contains 10 contributions to the academic literature all dealing with longevity risk and capital markets. Draft versions of the papers were presented at Longevity Six: The Sixth International Longevity Risk and Capital Markets Solutions Conference that was held in Sydney on 9-10 September 2010. It was hosted by the Australian Institute for Population Ageing Research, the Australian School of Business and the University of New South Wales. It was sponsored by PricewaterhouseCoopers, Australian Prudential Regulation Authority (APRA), Coventry Capital, Swiss Re, and Institute of Actuaries of Australia.Longevity Risk; Capital Market

In and out of Madagascar : dispersal to peripheral islands, insular speciation and diversification of Indian Ocean daisy trees (Psiadia, Asteraceae)

This study was supported by the European Union’s HOTSPOTS Training Network (MEST-2005-020561)Madagascar is surrounded by archipelagos varying widely in origin, age and structure. Although small and geologically young, these archipelagos have accumulated disproportionate numbers of unique lineages in comparison to Madagascar, highlighting the role of waif-dispersal and rapid in situ diversification processes in generating endemic biodiversity. We reconstruct the evolutionary and biogeographical history of the genus Psiadia (Asteraceae), a plant genus with near equal numbers of species in Madagascar and surrounding islands. Analyzing patterns and processes of diversification, we explain species accumulation on peripheral islands and aim to offer new insights on the origin and potential causes for diversification in the Madagascar and Indian Ocean Islands biodiversity hotspot. Our results provide support for an African origin of the group, with strong support for non-monophyly. Colonization of the Mascarenes took place by two evolutionary distinct lineages from Madagascar, via two independent dispersal events, each unique for their spatial and temporal properties. Significant shifts in diversification rate followed regional expansion, resulting in co-occurring and phenotypically convergent species on high-elevation volcanic slopes. Like other endemic island lineages, Psiadia have been highly successful in dispersing to and radiating on isolated oceanic islands, typified by high habitat diversity and dynamic ecosystems fuelled by continued geological activity. Results stress the important biogeographical role for Rodrigues in serving as an outlying stepping stone from which regional colonization took place. We discuss how isolated volcanic islands contribute to regional diversity by generating substantial numbers of endemic species on short temporal scales. Factors pertaining to the mode and tempo of archipelago formation and its geographical isolation strongly govern evolutionary pathways available for species diversification, and the potential for successful diversification of dispersed lineages, therefore, appears highly dependent on the timing of arrival, as habitat and resource properties change dramatically over the course of oceanic island evolution.Publisher PDFPeer reviewe

Identification of the gene encoding Brain Cell Membrane Protein 1 (BCMP1), a putative four-transmembrane protein distantly related to the Peripheral Myelin Protein 22 / Epithelial Membrane Proteins and the Claudins

BACKGROUND: A partial cDNA clone from dog thyroid presenting a very significant similarity with an uncharacterized mouse EST sequence was isolated fortuitously. We report here the identification of the complete mRNA and of the gene, the product of which was termed "brain cell membrane protein 1" (BCMP1). RESULTS: The 4 kb-long mRNA sequence exhibited an open-reading frame of only 543 b followed by a 3.2 kb-long 3' untranslated region containing several AUUUA instability motifs. Analysis of the encoded protein sequence identified the presence of four putative transmembrane domains. Similarity searches in protein domain databases identified partial sequence conservations with peripheral myelin protein 22 (PMP22)/ epithelial membrane proteins (EMPs) and Claudins, defining the encoded protein as representative of the existence of a novel subclass in this protein family. Northern-blot analysis of the expression of the corresponding mRNA in adult dog tissues revealed the presence of a huge amount of the 4 kb transcript in the brain. An EGFP-BCMP1 fusion protein expressed in transfected COS-7 cells exhibited a membranous localization as expected. The sequences encoding BCMP1 were assigned to chromosome X in dog, man and rat using radiation hybrid panels and were partly localized in the currently available human genome sequence. CONCLUSIONS: We have identified the existence in several mammalian species of a gene encoding a putative four-transmembrane protein, BCMP1, wich defines a novel subclass in this family of proteins. In dog at least, the corresponding mRNA is highly present in brain cells. The chromosomal localization of the gene in man makes of it a likely candidate gene for X-linked mental retardation

Investigating the peculiarities of sustainable energy policies in islands communities for smart grid development: insights from complexity science and agent based models

Initiatives and projects ranging from European islands to the Falklands and the Pacific Fiji islands are implementing renewable energy sources. They not only address the unique features of islands but also to reduce the economic vulnerability of small island states and in some cases, regenerate depopulated island communities and enhance socio-economic and ecological sustainability. Islands are often regarded as laboratories for, or precursors of, wider energy transitions and the “smart grid” innovation makes no exception. The “smart grid” is an umbrella term that covers modernization of both the transmission and active distribution grids and the different competing smart grid architectures could transform the electricity industry and the relations with consumers and prosumers. This paper asks two – relatively simple – questions: are there any socio-technical energy systems and dominant designs more prone to emerge depending on the topologies and scale of islands? How far can we learn and scale up lessons from the studies of island energy communities that are useful in other Complex Adaptive Systems (CAS) with greater scale and interconnectivity? This exploratory paper is part of on-going research project (CASCADE) to model smart grids as Agent Based Systems embracing concepts and techniques from Complexity Science. There are three key objectives. The paper initially summarizes the key particuliarities of island energy systems, including the scale and boundaries to the socio-technical system that combine to determine the appropriateness of different energy responses, balancing and optimizing the various combinations of distributed renewable generation, energy storage (including plug-in cars), and loads. From this, a provisional conceptual model will be presented which identifies the range of factors that (re)configure to influence the potential dissemination of new energy technologies within island communities and the range of agents that influence that process. The paper will build on an expanding literature on modelling societal transitions with cognitive agents and agent transformation to justify our modelling choices. Central to the question is how to represent the cognitive agents and their adoption of new technologies and adaptation patterns.Validation may benefit from data from the Bornholm smartgrid case and other case studies

Atrial fibrillation and its determinants after radiofrequency ablation of chronic common atrial flutter

Aim. Atrial fibrillation (AFib) is a major clinical issue and its occurrence is the main problem after catheter ablation of atrial flutter. The long-term occurrence of AFib after common atrial flutter ablation is still matter of debate as it may influence the therapeutic approach. So, the aim of our study was to analyze the determinants and the time course of AFib after radiofrequency catheter ablation of chronic common atrial flutter. Methods and Results. 89 consecutive patients (67.5 ± 12.0 yrs) underwent RF ablation of chronic common atrial flutter. 38.2 % had previous history of paroxysmal AFib. 51% had no underlying structural heart disease. Over a mean follow-up of 38 ± 13 months, the occurrence rate of AFib progressively increased up to 32.9% at the end of follow-up. The median occurrence time for AFib was 8 months. AFib occurrence was significantly associated with previous AFib history (P=0.01) but not with the presence of underlying heart disease (P=n.s.). Of particular interest, in our study, AFib never occurred in patients without previous AFib history. Palpitations after chronic common atrial flutter ablation was mostly related to AFib. Conclusion. In conclusion, after chronic common atrial flutter ablation, AFib incidence progressively increased over the follow-up in all patients. Patients with prior AFib history appeared to be a very high risk group. In these patients, closer monitoring is mandatory and the persistent risk of AFib recurrences may justify prolonged anticoagulation policy