Condensation of solids in space. Isotope fractionation in the model system C-O

The reported chemical fractionation of a single isotope O-16 under simulated space conditions provides the first experimental proof for the hypothesis that the oxygen isotopic anomaly (and other similar anomalies) seen in meteorites is a product of chemical fractionation in interstellar or circumstellar space. Work proposed on this subject was discontinued because a peer review determined that such effects could not possibly exist and that continued support of this project would be a wasted effort. A bibliography is included of articles generated during research in this area

Sources and geochemical evolution of cyanide and formaldehyde

The major source of cyanide has, in current paleoatmospheric models, been assumed to be the reaction of photodissociated thermospheric nitrogen with a limiting supply of stratospheric methane. Formaldehyde may be produced with more ease from an atmosphere of carbon dioxide as the dominant carbon species, and from carbonate in solution or sorbed in double layer hydroxide minerals. Potentially more important sources for cyanide and other carbon containing molecules are the partially photoprotected northern and southern auroral ovals where continuous currents reaching several mega-amperes induce ion-molecule reactions, extending into the lower stratosphere. In simulated environments of this kind, the cyanide ion is known to be produced from oxidized carbon species potentially more abundant than methane. Rainout of cyanide and formaldehyde place them in two different geochemical reaction reservoirs. In the anoxic Archean hydrosphere, about 1mM in Fe2(+), the cyanide ion would have been efficiently converted to the stable ferrocyanide complex Fe(CN) sub 6(4-), protecting it from the commonly considered fate of decomposition by hydrolysis, and eventually incorporating it in pyroaurite type minerals, most efficiently in green rust where it converts to insoluble ferriferrocyanide, prussian blue

Deterministic continutation of stochastic metastable equilibria via Lyapunov equations and ellipsoids

Numerical continuation methods for deterministic dynamical systems have been one of the most successful tools in applied dynamical systems theory. Continuation techniques have been employed in all branches of the natural sciences as well as in engineering to analyze ordinary, partial and delay differential equations. Here we show that the deterministic continuation algorithm for equilibrium points can be extended to track information about metastable equilibrium points of stochastic differential equations (SDEs). We stress that we do not develop a new technical tool but that we combine results and methods from probability theory, dynamical systems, numerical analysis, optimization and control theory into an algorithm that augments classical equilibrium continuation methods. In particular, we use ellipsoids defining regions of high concentration of sample paths. It is shown that these ellipsoids and the distances between them can be efficiently calculated using iterative methods that take advantage of the numerical continuation framework. We apply our method to a bistable neural competition model and a classical predator-prey system. Furthermore, we show how global assumptions on the flow can be incorporated - if they are available - by relating numerical continuation, Kramers' formula and Rayleigh iteration.Comment: 29 pages, 7 figures [Fig.7 reduced in quality due to arXiv size restrictions]; v2 - added Section 9 on Kramers' formula, additional computations, corrected typos, improved explanation

Population Ethics under Risk

Population axiology concerns how to evaluate populations in terms of their moral goodness, that is, how to order populations by the relations “is better than” and “is as good as”. The task has been to find an adequate theory about the moral value of states of affairs where the number of people, the quality of their lives, and their identities may vary. So far, this field has largely ignored issues about uncertainty and the conditions that have been discussed mostly pertain to the ranking of risk-free outcomes. Most public policy choices, however, are decisions under uncertainty, including policy choices that affect the size of a population. Here, we shall address the question of how to rank population prospects—that is, alternatives that contain uncertainty as to which population they will bring about—by the relations “is better than” and “is as good as”. We start by illustrating how well-known population axiologies can be extended to population prospect axiologies. And we show that new problems arise when extending population axiologies to prospects. In particular, traditional population axiologies lead to prospect-versions of the problems that they praised for avoiding in the risk-free settings. Finally, we identify an intuitive adequacy condition that, we contend, should be satisfied by any population prospect axiology, and show how given this condition, the impossibility theorems in population axiology can be extended to (non-trivial) impossibility theorems for population prospect axiology

The Construction of a New 'ism' - The Rhethorical Context of Architecture

By looking closer at the creation o f Deconstructivism, an architectural 'ism' that established itself on the architectural scene towards the end of the 1980's, this paper will discuss some of the different desires and rhetoric that may underlay the contemporary tendency for architects to establish working relations with philosophy. The introduction of the term "Deconstructivist" into architectural parlance can be traced back to the exhibition Deconstructivist Architecture held at the Museum of Modern Art in New York in 1988. The paper therefore returns to the material presented in the exhibition. Focusing on the text Deconstructivist Architecture by Mark Wigley in the exhibition catalogue, the paper begins with a brief discussion of the relationship between the philosophical term 'deconstruction' and the architectural term 'Deconstructivist' in order to reveal the underlying rhetoric behind the concept 'Deconstructivist Architecture'. This rhetoric is discussed further by investigating the exhibition's references to the avantgarde of Russian Constructivism and by considering the political connotations of architectural form. Continuing, the paper claims in opposition to the curators of Deconstructivist Architecture that the architecture of the exhibition gained its critical edge specifically through discourse, and concludes by arguing for the necessity of a rhetoric in contemporary architectural practice

On Agglutination and Coagulation.

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THE DEMOCRATIC BOUNDARY PROBLEM RECONSIDERED

Quem deve ter direito a participar em que decisões no processo democrático? Este “problema da delimitação” é uma questão central para a democracia, e tem importância tanto teórica como prática. Todas as diferentes noções de democracia têm, pelo menos, uma coisa em comum: uma referência a uma comunidade de indivíduos, “um povo”, que toma decisões de forma democrática. No entanto, que uma decisão seja tomada de acordo com um método democrático por um determinado grupo de pessoas não é suficiente para que a decisão seja democrática ou satisfatória numa perspectiva democrática. O grupo tem também de ser o grupo certo. Mas o que é que faz com que um grupo seja o grupo certo? Tem sido surpreendentemente difícil determinar os critérios com os quais devemos identificar os membros do povo que têm o direito de participar em decisões colectivas. Neste artigo, irei revisitar alguns dos problemas discutidos no meu artigo de 2005 à luz de críticas recentes e da discussão da minha posição na literatura, e abordarei algumas questões novas.Who should have a right to take part in which decisions in democratic decision making? This “boundary problem” is a central issue for democracy and is of both practical and theoretical import. If nothing else, all different notions of democracy have one thing in common: a reference to a community of individuals, “a people”, who takes decision in a democratic fashion. However, that a decision is made with a democratic decision method by a certain group of people doesn’t suffice for making the decision democratic or satisfactory from a democratic perspective. The group also has to be the right one. But what makes a group the right one? The criteria by which to identify the members of the people entitled to participate in collective decisions have been surprisingly difficult to pin down. In this paper, I shall revisit some of the problems discussed in my 2005 paper in light of some recent criticism and discussion of my position in the literature, and address a number of new issues