Some statistical aspects of the long-term gill net monitoring programme for pike Esox lucius in Windermere (English Lake District)

For more than 55 years, data have been collected on the population of pike Esox lucius in Windermere, first by the Freshwater Biological Association (FBA) and, since 1989, by the Institute of Freshwater Ecology (IFE) of the NERC Centre for Ecology and Hydrology. The aim of this article is to explore some methodological and statistical issues associated with the precision of pike gill net catches and catch-per-unit-effort (CPUE) data, further to those examined by Bagenal (1972) and especially in the light of the current deployment within the Windermere long-term sampling programme. Specifically, consideration is given to the precision of catch estimates from gill netting, including the effects of sampling different locations, the effectiveness of sampling for distinguishing between years, and the effects of changing fishing effort

R&D Depreciation Rates in the 2007 R&D Satellite Account

This paper is part of a series that provides the details behind the Bureau of Economic Analysis’s (BEA) satellite account on research and development (R&D) activity. In the current work, the focus is on industry-specific depreciation rates for business R&D capital. This paper begins by discussing the literature on R&D depreciation rates. It then describes how the rates in the 2007 satellite account were chosen from the related findings.

The Effects of Low-Valued Transactions on the Quality of U.S. International Export Estimates, 1994-1998

This paper uses data from the U.S. Census Bureau Annual Survey of Manufactures (ASM) to examine the effects that a growth of low-valued transactions likely has on the quality of export estimates provided in the U.S. International Trade in Goods and Services (FT-990) series. These transactions, valued at less than $2,500, do not legally require the filing of export declarations. As a result, they are often not captured in the administrative records data used to construct FT-990 estimates. By comparing industry-level estimates created from the ASM to related FT-990 estimates, this paper estimates that the undercounting of low-valued transactions in the FT-990 export series increases by roughly$30 billion over the period of 1994-1997. It also finds that regression analysis provides little insight into the undercounting issue as results are primarily driven by industries whose contributions to total manufacturing exports are small.

The Fish Funnel: A Trawl Modification to Reduce Fish Escapement

In the Gulf of Mexico there is a need to assess the potential of underutilized fish resource stocks before a commercial fishery develops. Standard sampling trawls used in the Gulf are ineffective for sampling the resource, so larger, high opening, bottom trawls have been introduced. The larger trawls are more effective, but most of the faster swimming fish species are able to escape these nets, especially during haul back. To reduce fish escapement, webbing panels, attached inside the trawls ahead of the cod ends, were tested. Initial tests were conducted with two single panel designs--a fish flap and a "floppa." Neither design reduced fish escapement. The floppa distorted the trawl webbing and actually increased fish escapement. A multi-panel conical funnel design (the fish funnel) was tested and found to increase fish retention by trapping the fish after they passed through it. When used in combination with a technique known as pulsing the trawl, the fish funnel substantially increased trawl catch rates with no indication of fish escapement

New Applications of Radio Frequency Identification Stations for Monitoring Fish Passage through Headwater Road Crossings and Natural Reaches

Within the Ouachita National Forest, roads and streams intersect each other thousands of times. Many of these road crossings alter stream hydrology and potentially limit longitudinal fish movement. To investigate the potential impacts of these road crossings on fish passage, we monitored movements of 3 native fish species (n = 2,171) individually tagged with radio frequency identification (RFID) tags in 2012 and 2013. We installed solar-powered RFID stations in 2 streams with road crossings and 2 reference streams without road crossings. Each of the 4 monitoring stations included a pair of antennas bracketing a road crossing (or similarly-sized natural reach) to continuously detect upstream or downstream passage. To monitor natural reference streams, we avoided full-duplex RFID technology, which would have required rigid in-stream structures. Alternatively, we utilized new applications of RFID technology such as direct in-stream installation of half-duplex wire antennas and figure-eight crossover antenna designs. These techniques appear promising, but technical difficulties limited the consistency of fish passage detection and consequently limited the strength of ecological conclusions. Even so, we report evidence that fish passed at significantly higher rates across reference reaches than reaches with road crossings. Furthermore, Creek Chub (Semotilus atromaculatus) passed reference reaches at significantly higher rates than Highland Stonerollers (Campostoma spadiceum), which passed at higher rates than Longear Sunfish (Lepomis megalotis). Stream intermittency appeared to exacerbate reduced passage rates associated with the road crossings

Harnessing Technology: new modes of technology-enhanced learning: opportunities and challenges

A report commissioned by Becta to explore the potential impact on education, staff and learners of new modes of technology enhanced learning, envisaged as becoming available in subsequent years. A generative framework, developed by the researchers is described, which was used as an analytical tool to relate the possibilities of the technology described to learning and teaching activities. This report is part of the curriculum and pedagogy strand of Becta's programme of managed research in support of the development of Harnessing Technology: Next Generation Learning 2008-14. A system-wide strategy for technology in education and skills. Between April 2008 and March 2009, the project carried out research, in three iterative phases, into the future of learning with technology. The research has drawn from, and aims to inform, all UK education sectors

On the optimal design of wall-to-wall heat transport

We consider the problem of optimizing heat transport through an incompressible fluid layer. Modeling passive scalar transport by advection-diffusion, we maximize the mean rate of total transport by a divergence-free velocity field. Subject to various boundary conditions and intensity constraints, we prove that the maximal rate of transport scales linearly in the r.m.s. kinetic energy and, up to possible logarithmic corrections, as the $1/3$rd power of the mean enstrophy in the advective regime. This makes rigorous a previous prediction on the near optimality of convection rolls for energy-constrained transport. Optimal designs for enstrophy-constrained transport are significantly more difficult to describe: we introduce a "branching" flow design with an unbounded number of degrees of freedom and prove it achieves nearly optimal transport. The main technical tool behind these results is a variational principle for evaluating the transport of candidate designs. The principle admits dual formulations for bounding transport from above and below. While the upper bound is closely related to the "background method", the lower bound reveals a connection between the optimal design problems considered herein and other apparently related model problems from mathematical materials science. These connections serve to motivate designs.Comment: Minor revisions from review. To appear in Comm. Pure Appl. Mat

Control of a nonlinear underactuated system with adaptation, numerical stability verification, and the use of the LQR Trees algorithm

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 54).Underactuated robotics, though surrounded by an established body of work, has certain limitations when nonlinear adaptive control principles are applied. This thesis applies a nonlinear adaptative controller that avoids many of these limitations using alterations inspired by the control of a similar underactuated system, the cart-pole. Due to the complexity of the system, a sums-of-squares MATLAB toolbox is used to generate a suitable Lyapunov Candidate used for proofs of stability, with claims of local stability made using Barbalat's Lemma. This provides us with a local domain of attraction for the altered classical nonlinear adaptive controller. In addition, the algorithm known as LQR Trees is applied to the system in order to create a controller with a larger region of attraction and lower torque requirements, though without an adaptive component. Both control systems are implemented in simulations using MATLAB.by Ian Charles Rust.S.B