Response of Bird Populations to Long-term Changes in Local Vegetation and Regional Forest Cover

We analyzed data from a woodland site for a 59-year period to determine whether changes in bird populations are related to changes in the diversity and relative abundance of woody plant species even when vegetation structure, degree of forest fragmentation in the surrounding landscape, and regional changes in bird populations are taken into account. Principal component analyses generated vegetation factors encompassing variables such as total basal area, shrub density, basal area of common tree species, and measures of tree and shrub species diversity. We also calculated a forest edge/ forest area index based on GIS analysis of the landscape within 2 km of the study site. Poisson regression models revealed relationships between these covariates and population changes for 19 bird species and for seven groups of species characterized by similar migration strategies or habitat requirements. All groups of habitat specialists showed a positive relationship with the first vegetation factor, which indicates that they declined as total basal area and dominance of oaks and maples increased and as tree and shrub diversity decreased. This suggests that floristic diversity may be important for determining habitat quality. Bird species associated with the shrub layer and with hemlock stands showed positive relationships with the second vegetation factor, suggesting that the recent decline in eastern hemlocks (Tsuga canadensis) because of hemlock woolly adelgid (Adelges tsugae) had an adverse impact on these species. Forest migrants, shrub-layer specialists, long-distance migrants and permanent residents showed negative relationships with the forest edge/forest interior index, indicating that conservation efforts to protect bird communities should take the wider landscape into account. The strongest relationship for most species and species groups was with the first vegetation factor, which suggests that species composition and diversity of trees and shrubs may be especially important in determining abundance of many forest bird species

THE IMPACT OF POPULATION GROWTH ON RESIDENTIAL PROPERTY TAXES

A multivariate model of the effect of population on local fiscal behavior, assessed value of property and average single family home values is estimated using cross-sectional data from Oregon. Regression results suggest that property tax levies are unit elastic with respect to population, that the total assessed value of property increases less than proportionally with population, and that the average value of a single family home increases with population. These results imply a positive relationship between population and both property tax rates and the tax bill of the average single family homeowner. Ceteris paribus, increases in average residential property taxes are associated with increases in population.Public Economics,

Pneumatic separator gives quick release to heavy loads

Pneumatic separator, using applied pressure, quickly releases restraining devices securing heavy loads. With minor modifications this separator can be used as a coupling device

Integrating Information Literacy into the Virtual University: A Course Model

published or submitted for publicatio

Dynamic elasticity by the theory of characteristics

Method of characteristics for analysis of elastic wave equations in Cartesian coordinate

Quantitative Analysis of Electrotonic Structure and Membrane Properties of NMDA-Activated Lamprey Spinal Neurons

Parameter optimization methods were used to quantitatively analyze frequency-domain-voltage-clamp data of NMDA-activated lamprey spinal neurons simultaneously over a wide range of membrane potentials. A neuronal cable model was used to explicitly take into account receptors located on the dendritic trees. The driving point membrane admittance was measured from the cell soma in response to a Fourier synthesized point voltage clamp stimulus. The data were fitted to an equivalent cable model consisting of a single lumped soma compartment coupled resistively to a series of equal dendritic compartments. The model contains voltage-dependent NMDA sensitive (INMDA), slow potassium (IK), and leakage (IL) currents. Both the passive cable properties and the voltage dependence of ion channel kinetics were estimated, including the electrotonic structure of the cell, the steady-state gating characteristics, and the time constants for particular voltage- and time-dependent ionic conductances. An alternate kinetic formulation was developed that consisted of steady-state values for the gating parameters and their time constants at half-activation values as well as slopes of these parameters at half-activation. This procedure allowed independent restrictions on the magnitude and slope of both the steady-state gating variable and its associated time constant. Quantitative estimates of the voltage-dependent membrane ion conductances and their kinetic parameters were used to solve the nonlinear equations describing dynamic responses. The model accurately predicts current clamp responses and is consistent with experimentally measured TTX-resistant NMDA-induced patterned activity. In summary, an analysis method is developed that provides a pragmatic approach to quantitatively describe a nonlinear neuronal system

Information seeking in the Humanities: physicality and digitality

This paper presents a brief overview of a research project that is examining the information seeking practices of humanities scholars. The results of this project are being used to develop digital resources to better support these work activities. Initial findings from a recent set of interviews is offered, revealing the importance of physical artefacts in the humanities scholars’ research processes and the limitations of digital resources. Finally, further work that is soon to be undertaken is summarised, and it is hoped that after participation in this workshop these ideas will be refined

Space station full-scale docking/berthing mechanisms development

One of the most critical operational functions for the space station is the orbital docking between the station and the STS orbiter. The program to design, fabricate, and test docking/berthing mechanisms for the space station is described. The design reflects space station overall requirements and consists of two mating docking mechanism halves. One half is designed for use on the shuttle orbiter and incorporates capture and energy attenuation systems using computer controlled electromechanical actuators and/or attenuators. The mating half incorporates a flexible feature to allow two degrees of freedom at the module-to-module interface of the space station pressurized habitat volumes. The design concepts developed for the prototype units may be used for the first space station flight hardware