Application of the stochastic closure theory to the Townsend-Perry constants.

We compare the stochastic closure theory (SCT) to the Townsend-Perry constants as estimated from measurements in the Flow Physic Facility (FPF) at the University of New Hampshire. First, we explain the derivation of the Townsend-Perry constants, which were originally formulated by Meneveau and Marusic, in analogy with a Gaussian distribution. However, this was not supported by the data.

Predicting impacts of chemicals from organisms to ecosystem service delivery: A case study of insecticide impacts on a freshwater lake.

Assessing and managing risks of anthropogenic activities to ecological systems is necessary to ensure sustained delivery of ecosystem services for future generations. Ecological models provide a means of quantitatively linking measured risk assessment endpoints with protection goals, by integrating potential chemical effects with species life history, ecological interactions, environmental drivers and other potential stressors. Here we demonstrate how an ecosystem modeling approach can be used to quantify insecticide-induced impacts on ecosystem services provided by a lake from toxicity data for organism-level endpoints.

Predicting impacts of chemicals from organisms to ecosystem service delivery: A case study of endocrine disruptor effects on trout.

We demonstrate how mechanistic modeling can be used to predict whether and how biological responses to chemicals at (sub)organismal levels in model species (i.e., what we typically measure) translate into impacts on ecosystem service delivery (i.

Parameter dependence of high-frequency nonlinear oscillations and intrinsic chaos in short GaAs/(Al, Ga)As superlattices.

We explore the design parameter space of short (5-25 period), n-doped, Ga/(Al,Ga)As semiconductor superlattices (SSLs) in the sequential resonant tunneling regime. We consider SSLs at cool (77 K) and warm (295 K) temperatures, simulating the electronic response to variations in (a) the number of SSL periods, (b) the contact conductivity, and (c) the strength of disorder (aperiodicities). Our analysis shows that the chaotic dynamical phases exist on a number of sub-manifolds of codimension zero within the design parameter space.

Effects of fish movement assumptions on the design of a marine protected area to protect an overfished stock.

Marine Protected Areas (MPA) are important management tools shown to protect marine organisms, restore biomass, and increase fisheries yields. While MPAs have been successful in meeting these goals for many relatively sedentary species, highly mobile organisms may get few benefits from this type of spatial protection due to their frequent movement outside the protected area. The use of a large MPA can compensate for extensive movement, but testing this empirically is challenging, as it requires both large areas and sufficient time series to draw conclusions.

A framework for predicting impacts on ecosystem services from (sub)organismal responses to chemicals.

Protection of ecosystem services is increasingly emphasized as a risk-assessment goal, but there are wide gaps between current ecological risk-assessment endpoints and potential effects on services provided by ecosystems. The authors present a framework that links common ecotoxicological endpoints to chemical impacts on populations and communities and the ecosystem services that they provide. This framework builds on considerable advances in mechanistic effects models designed to span multiple levels of biological organization and account for various types of biological interactions and feedbacks.

Sub-Gaussian behavior of the Townsend-Perry constants in turbulent boundary layers.

A theory is developed to explain the sub-Gaussian behavior of the Townsend-Perry constants (A_{p}) recently measured for high-order fluctuation moments in turbulent boundary layers. It yields the generalized logarithmic law for high-order moments and A_{p}/A_{1}=(ℓ^{*})^{ζ_{p}/p-ζ_{1}}C_{p}^{1/p}/C_{1}, where ζ_{p} are the Kolmogorov-Obukhov-She-Leveque scaling characterizing intermittence effects; ℓ^{*}=1/225 is the only free parameter describing a specific ratio between inertial and energy-containing eddy sizes; C_{p} are raw moments of a Gaussian with unity mean and variance. The predicted A_{p}/A_{1} are in good agreement with experimental data.

A dynamic energy budget (DEB) model for the energy usage and reproduction of the Icelandic capelin (Mallotus villosus).

We apply a dynamic energy budget (DEB) model to the Icelandic capelin (Mallotus villosus) and introduce a new state variable to capture the roe production of individual fish. Species-specific coefficients are found for the capelin such as the shape coefficient and the Arrhenius temperature. We show how to link the DEB model to measurable quantities such as weight, length, fat, and roe content.

Meandering fluid streams in the presence of flow-rate fluctuations.

We report that meandering of a rivulet flowing down a nonerodible, partially wetting incline is triggered by flow-rate fluctuations and sustained by external noise forcing. In our experiments, the former is provided by an electronically controlled valve, and the latter is due to fluid droplets left on the surface by previous meanderings. We observe power-law behavior of the averaged spectrum of the deviations of the stream from its center line, which rules out the existence of a preferred wavelength in ongoing meandering.