Robust monomer-distribution biosignatures in evolving digital biota

Because organisms synthesize component molecules at rates that reflect those molecules' adaptive utility, we expect a population of biota to leave a distinctive chemical signature on their environment that is anomalous given the local (abiotic) chemistry. We observe the same effect in the distribution of computer instructions used by an evolving population of digital organisms, and characterize the robustness of the evolved signature with respect to a number of different changes in the system's physics. The observed instruction abundance anomaly has features that are consistent over a large number of evolutionary trials and alterations in system parameters, which makes it a candidate for a non-Earth-centric life-diagnosticComment: 22 pages, 4 figures, 1 table. Supplementary Material available from C

Bound States of D-Branes and the Non-Abelian Born-Infeld Action

We attempt to settle the issue as to what is the correct non-abelian generalisation of the Born-Infeld action, via a consideration of the two-loop $\beta$--function for the non-abelian background gauge field in open string theory. An analysis of the bosonic theory alone shows the recent proposal of Tseytlin's to be somewhat lacking. For the superstring, however, this proposal would seem to be correct, and not just within the approximation used in \cite{tseytlin}. Since it is this latter case that is relevant to the description of D-branes we, in effect, obtain an independent verification of Tseytlin's result. Some issues involved in the concept of non-abelian T--duality are discussed; and it is shown how the interaction between separated and parallel branes, in the form of massive string states, emerges.Comment: 24 pages, 4 eps figures, LaTeX. Further comments concerning earlier work added, minor typos corrected. Version to be published in Nucl. Phys.

White-tailed Deer in Southeastern Minnesota: Winter Observations

Food habits, movements, vegetation type use, and bedding of white-tailed deer (Odocoileus virginianus borealis) were observed while snow-tracking in southeastern Minnesota. Waste corn (Zea Mays) was the most important food item. Three dogwoods (Cornus racemosa, C. rugosa, C. alternifolia), all non-commercial forest species, were the most important for browse. Acorns were unavailable due to crop failure. Six trails made in less than 24 hours covered more than 1 mile each, straight line distance. The longest was 31/s miles. Snow did not appear to affect movements. About two-thirds of the beds were on wooded uplands. Browsing areas appeared dependent on bedding locations which appeared dependent on upland field location

How Many Environmental Plaintiffs Are Still Standing?

Standing is easy to describe but difficult to apply. At a minimum, standing requires three elements: (1) injury-in-fact; (2) traceability to conduct of the defendant; and (3) that a favorable decision could provide redress for the injury. This Note outlines the development of the standing doctrine from Lujan v. Defenders of Wildlife through Summers v. Earth Island Institute and examines how several courts have applied this standard to their cases. It also analyzes Pollack v. Department of Justice. It proposes an approach that demands more than pleadings but removes the court\u27s license to pre-litigate the merits of the case under the guise of the standing doctrine. And finally, it argues that standing should be retired when it comes to what are now traditional environmental claims because the elements of standing are so intertwined with the merits of the case

Coordinate representation of particle dynamics in AdS and in generic static spacetimes

We discuss the quantum dynamics of a particle in static curved spacetimes in a coordinate representation. The scheme is based on the analysis of the squared energy operator E^2, which is quadratic in momenta and contains a scalar curvature term. Our main emphasis is on AdS spaces, where this term is fixed by the isometry group. As a byproduct the isometry generators are constructed and the energy spectrum is reproduced. In the massless case the conformal symmetry is realized as well. We show the equivalence between this quantization and the covariant quantization, based on the Klein-Gordon type equation in AdS. We further demonstrate that the two quantization methods in an arbitrary (N+1)-dimensional static spacetime are equivalent to each other if the scalar curvature terms both in the operator E^2 and in the Klein-Gordon type equation have the same coefficient equal to (N-1)/(4N).Comment: 14 pages, no figures, typos correcte

Can we constrain interior structure of rocky exoplanets from mass and radius measurements?

We present an inversion method based on Bayesian analysis to constrain the interior structure of terrestrial exoplanets, in the form of chemical composition of the mantle and core size. Specifically, we identify what parts of the interior structure of terrestrial exoplanets can be determined from observations of mass, radius, and stellar elemental abundances. We perform a full probabilistic inverse analysis to formally account for observational and model uncertainties and obtain confidence regions of interior structure models. This enables us to characterize how model variability depends on data and associated uncertainties. We test our method on terrestrial solar system planets and find that our model predictions are consistent with independent estimates. Furthermore, we apply our method to synthetic exoplanets up to 10 Earth masses and up to 1.7 Earth radii as well as to exoplanet Kepler-36b. Importantly, the inversion strategy proposed here provides a framework for understanding the level of precision required to characterize the interior of exoplanets. Our main conclusions are: (1) observations of mass and radius are sufficient to constrain core size; (2) stellar elemental abundances (Fe, Si, Mg) are key constraints to reduce degeneracy in interior structure models and to constrain mantle composition; (3) the inherent degeneracy in determining interior structure from mass and radius observations does not only depend on measurement accuracies but also on the actual size and density of the exoplanet. We argue that precise observations of stellar elemental abundances are central in order to place constraints on planetary bulk composition and to reduce model degeneracy. [...]Comment: 19 pages, 18 figures, accepted in Astronomy & Astrophysics (no changes to previous version

An Exact Algorithm for TSP in Degree-3 Graphs via Circuit Procedure and Amortization on Connectivity Structure

The paper presents an O^*(1.2312^n)-time and polynomial-space algorithm for the traveling salesman problem in an n-vertex graph with maximum degree 3. This improves the previous time bounds of O^*(1.251^n) by Iwama and Nakashima and O^*(1.260^n) by Eppstein. Our algorithm is a simple branch-and-search algorithm. The only branch rule is designed on a cut-circuit structure of a graph induced by unprocessed edges. To improve a time bound by a simple analysis on measure and conquer, we introduce an amortization scheme over the cut-circuit structure by defining the measure of an instance to be the sum of not only weights of vertices but also weights of connected components of the induced graph.Comment: 24 pages and 4 figure

Development of a carbon fibre composite active mirror: Design and testing

Carbon fibre composite technology for lightweight mirrors is gaining increasing interest in the space- and ground-based astronomical communities for its low weight, ease of manufacturing, excellent thermal qualities and robustness. We present here first results of a project to design and produce a 27 cm diameter deformable carbon fibre composite mirror. The aim was to produce a high surface form accuracy as well as low surface roughness. As part of this programme, a passive mirror was developed to investigate stability and coating issues. Results from the manufacturing and polishing process are reported here. We also present results of a mechanical and thermal finite element analysis, as well as early experimental findings of the deformable mirror. Possible applications and future work are discussed.Comment: Accepted by Optical Engineering. Figures 1-7 on http://www.star.ucl.ac.uk/~sk/OEpaper_files

Renormalization Group Flows in Sigma--Models Coupled to Two--Dimensional Dynamical Gravity

We consider a bosonic \s--model coupled to two--dimensional gravity. In the semiclassical limit, $c\rightarrow -\infty$, we compute the gravity dressing of the \b--functions at two--loop order in the matter fields. We find that the corrections due to the presence of dynamical gravity are {\em not} expressible simply in terms of a multiplicative factor as previously obtained at the one--loop level. Our result indicates that the critical points of the theory are nontrivially influenced and modified by the induced gravity.Comment: Latex file, 18 pages plus 7 figure

Enduring Effects of Infant Emotional Security on Preschooler Adaptation to Interparental Conflict

Emotional security theory illustrates the significance of children’s reactions to interparental conflict as a mediator of the associations between interparental conflict and children’s well-being. Less is known about infants’ emotional security. The current study assessed the stability of emotional security over infancy through preschool years. We also assessed whether infant emotional insecurity mediated between interparental conflict during infancy and preschooler adjustment. Seventy-four families with infants aged 6–14 months participated at Time 1. Parents engaged in a conflict resolution task with their infants present. Families returned when children were 3–5 years old (Time 2). Families engaged in the same conflict resolution task and parents additionally completed the Strengths and Difficulty Questionnaire to assess preschooler adjustment. Cluster analyses revealed two classes of infants based on conflict responses at Time 1: secure and insecure. The insecure group demonstrated higher levels of distress, frustration, physical frustration, and dysregulation compared to the secure group. These classifications remained relatively stable over Times 1 and 2. Infant emotional security mediated associations between Time 1 interparental conflict and preschooler adjustment, even when considering preschooler emotional security. Our results highlight the lasting legacy of destructive conflict on infants’ still developing security systems