A two-compartment model for understanding the simulated three-dimensional circulation in Prince William Sound, Alaska

A two-compartment model of Prince William Sound (PWS), Alaska, is developed. One compartment, corresponding to the southern PWS, represents advective phenomena, while the other is dominated by diffusion. This simple model is shown to reproduce rather well the temporal evolution of the mass of a passive tracer contained in PWS simulated by a complex, three-dimensional model under five types of surface forcing. The three parameters of the box-model have clear physical meanings, which helps to understand the hydrodynamics of PWS. In particular, the fraction of the flow entering the northern PWS is estimated, as well as the turnover time of the two regions considered

Feasibility study for a Scanning Celestial Attitude Determination System /SCADS/ for three axis attitude determination at a Command and Data Acquisition /CDA/ station Final report

Scanning Celestial Attitude Determination System /SCADS/ for three axis attitude determination at Command and Data Acquisition /CDA/ statio

Scaling properties of protein family phylogenies

One of the classical questions in evolutionary biology is how evolutionary processes are coupled at the gene and species level. With this motivation, we compare the topological properties (mainly the depth scaling, as a characterization of balance) of a large set of protein phylogenies with a set of species phylogenies. The comparative analysis shows that both sets of phylogenies share remarkably similar scaling behavior, suggesting the universality of branching rules and of the evolutionary processes that drive biological diversification from gene to species level. In order to explain such generality, we propose a simple model which allows us to estimate the proportion of evolvability/robustness needed to approximate the scaling behavior observed in the phylogenies, highlighting the relevance of the robustness of a biological system (species or protein) in the scaling properties of the phylogenetic trees. Thus, the rules that govern the incapability of a biological system to diversify are equally relevant both at the gene and at the species level.Comment: Replaced with final published versio

Can sexual selection drive female life histories? A comparative study on Galliform birds

Sexual selection is an important driver of many of the most spectacular morphological traits that we find in the animal kingdom (for example see Andersson, 1994). As such, sexual selection is most often emphasized as

Protecting biodiversity in British Columbia: Recommendations for developing species at risk legislation

British Columbia has the greatest biological diversity of any province or territory in Canada. Yet increasing numbers of species in British Columbia are threatened with extinction. The current patchwork of provincial laws and regulations has not effectively prevented species declines. Recently, the Provincial Government has committed to enacting an endangered species law. Drawing upon our scientific and legal expertise, we offer recommendations for key features of endangered species legislation that build upon strengths and avoid weaknesses observed elsewhere. We recommend striking an independent Oversight Committee to provide recommendations about listing species, organize Recovery Teams, and monitor the efficacy of actions taken. Recovery Teams would evaluate and prioritize potential actions for individual species or groups of species that face common threats or live in a common area, based on best available evidence (including natural and social science and Indigenous Knowledge). Our recommendations focus on implementing an adaptive approach, with ongoing and transparent monitoring and reporting, to reduce delays between determining when a species is at risk and taking effective actions to save it. We urge lawmakers to include this strong evidentiary basis for species recovery as they tackle the scientific and socioeconomic challenges of building an effective species at risk Act

Protecting biodiversity in British Columbia: Recommendations for developing species at risk legislation

British Columbia has the greatest biological diversity of any province or territory in Canada. Yet increasing numbers of species in British Columbia are threatened with extinction. The current patchwork of provincial laws and regulations has not effectively prevented species declines. Recently, the Provincial Government has committed to enacting an endangered species law. Drawing upon our scientific and legal expertise, we offer recommendations for key features of endangered species legislation that build upon strengths and avoid weaknesses observed elsewhere. We recommend striking an independent Oversight Committee to provide recommendations about listing species, organize Recovery Teams, and monitor the efficacy of actions taken. Recovery Teams would evaluate and prioritize potential actions for individual species or groups of species that face common threats or live in a common area, based on best available evidence (including natural and social science and Indigenous Knowledge). Our recommendations focus on implementing an adaptive approach, with ongoing and transparent monitoring and reporting, to reduce delays between determining when a species is at risk and taking effective actions to save it. We urge lawmakers to include this strong evidentiary basis for species recovery as they tackle the scientific and socioeconomic challenges of building an effective species at risk Act

Mechanism for export of sediment-derived iron in an upwelling regime

Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 39 (2012): L03601, doi:10.1029/2011GL050366.Model simulations performed with a three-dimensional, high-resolution, process study ocean model of eastern boundary upwelling systems are used to describe a mechanism that efficiently transports sediment-derived dissolved iron offshore in the subsurface through the bottom boundary layer (BBL) during downwelling-favorable wind events. In the model, sediment-derived iron accumulates in the BBL on the outer shelf when the winds are upwelling-favorable. When the wind reverses, the iron-laden BBL is mixed into the water column and transported offshore along isopycnals that intersect the bottom. Depending on the frequency of wind reversal, between 10–50% of the shelf sediment-derived iron flux is exported offshore through this previously unidentified subsurface pathway. If this mechanism operates on all coastal upwelling regimes, the global export of sediment-derived iron to the open ocean would be equivalent to ten times larger than the estimated source of dissolved iron from aerosols.NSF supported this work.2012-08-1

Functional determinants for general self-adjoint extensions of Laplace-type operators resulting from the generalized cone

In this article we consider the zeta regularized determinant of Laplace-type operators on the generalized cone. For {\it arbitrary} self-adjoint extensions of a matrix of singular ordinary differential operators modelled on the generalized cone, a closed expression for the determinant is given. The result involves a determinant of an endomorphism of a finite-dimensional vector space, the endomorphism encoding the self-adjoint extension chosen. For particular examples, like the Friedrich's extension, the answer is easily extracted from the general result. In combination with \cite{BKD}, a closed expression for the determinant of an arbitrary self-adjoint extension of the full Laplace-type operator on the generalized cone can be obtained.Comment: 27 pages, 2 figures; to appear in Manuscripta Mathematic

The ubiquitous ζ\zeta-function and some of its "usual" and "unusual" meromorphic properties

In this contribution we announce a complete classification and new exotic phenomena of the meromorphic structure of \z-functions associated to conic manifolds proved in \cite{KLP1}. In particular, we show that the meromorphic extensions of these \z-functions have, in general, countably many logarithmic branch cuts on the nonpositive real axis and unusual locations of poles with arbitrarily large multiplicity. Moreover, we give a precise algebraic-combinatorial formula to compute the coefficients of the leading order terms of the singularities.Comment: Paper presented at the 8th Workshop on Quantum Field Theory under the Influence of External Conditions (Leipzig, Germany, 16-21 September, 2007

Converting Endangered Species Categories to Probabilities of Extinction for Phylogenetic Conservation Prioritization

Categories of imperilment like the global IUCN Red List have been transformed to probabilities of extinction and used to rank species by the amount of imperiled evolutionary history they represent (e.g. by the Edge of Existence programme). We investigate the stability of such lists when ranks are converted to probabilities of extinction under different scenarios.Using a simple example and computer simulation, we show that preserving the categories when converting such list designations to probabilities of extinction does not guarantee the stability of the resulting lists.Care must be taken when choosing a suitable transformation, especially if conservation dollars are allocated to species in a ranked fashion. We advocate routine sensitivity analyses