Identifying biotic determinants of historic American eel (Anguilla rostrata) distributions

Traditionally, ecologists studying large scale patterns in species distributions emphasize abiotic variables over biotic interactions. Noting that both abiotic & biotic variables likely determine distributions of all organisms, many ecologists now aim for a more comprehensive view of species distributions, inclusive of both abiotic and biotic components (Soberón 2007)

The Interdependence of School Outcomes and School and Neighborhood Crime

In this paper, we estimate the effects of neighborhood crime and in-school crime on educational outcomes for elementary and secondary schools in the city of Atlanta over the period 1999 to 2002. We specify a model that accounts for the joint determination of both types of crime along with school outcomes. Despite the large empirical literature on both education production functions and crime incidence, there has been little empirical work on crime's effect on school outcomes. One exception is Grogger (1997) who used individual data from the High School and Beyond study to estimate the effect of school violence on measures of individual student performance. After controlling for individual and school characteristics, he found that moderate and severe levels of school violence had substantial negative consequences for school outcomes. Our study both updates and expands on his work, using current data and better measures of neighborhood violence. Working Paper 07-1

Experimenting with undergraduate practicals

In my experience the prescriptive nature of many undergraduate practicals restricts the scope for students to apply and develop their subject-specific knowledge. In addition, the nature of such practicals places limitations on their effectiveness for development of problem solving, team working and transferable skills. In recognition of this, a number of laboratory practicals in physical chemistry have been developed (some from existing traditional scripts) which feature clearly formulated and explicit objectives, but which omit detailed instructions to a greater or lesser extent. One particular aspect of these practicals is that the onus is placed on students to design a viable experimental approach in order to achieve the stated objectives and to reflect critically on their work. In this respect some of the practicals may be considered as structured mini-projects. Another implicit aspect is an attempt to encourage students to de-compartmentalise their subject knowledge (e.g. organic mechanisms in a ‘physical’ chemistry practical).The practicals have been used successfully at levels 1 and 2 during the past two years at Keele, and although the approach described has been applied to laboratory work in physical chemistry, there is no reason why it cannot be applied more generally

Industry-linked context-based chemistry practicals

There is considerable evidence that the use of tangible contexts enriches the learning experience for students. In view of this, the author has developed two ‘industry-linked context-based chemistry practicals’ that illustrate the importance of core chemistry topics within commercial/industrial contexts. A common feature of the practicals is that the students work with actual commercial samples and compare their data with that published by the two companies. The principal features of the two practicals are described and contrasted with conventional practicals. Finally, the results of a student evaluation of the practicals are reported

Remotely triggered scaffolds for controlled release of pharmaceuticals

Fe3O4-Au hybrid nanoparticles (HNPs) have shown increasing potential for biomedical applications such as image guided stimuli responsive drug delivery. Incorporation of the unique properties of HNPs into thermally responsive scaffolds holds great potential for future biomedical applications. Here we successfully fabricated smart scaffolds based on thermo-responsive poly(N-isopropylacrylamide) (pNiPAM). Nanoparticles providing localized trigger of heating when irradiated with a short laser burst were found to give rise to remote control of bulk polymer shrinkage. Gold-coated iron oxide nanoparticles were synthesized using wet chemical precipitation methods followed by electrochemical coating. After subsequent functionalization of particles with allyl methyl sulfide, mercaptodecane, cysteamine and poly(ethylene glycol) thiol to enhance stability, detailed biological safety was determined using live/dead staining and cell membrane integrity studies through lactate dehydrogenase (LDH) quantification. The PEG coated HNPs did not show significant cytotoxic effect or adverse cellular response on exposure to 7F2 cells (p < 0.05) and were carried forward for scaffold incorporation. The pNiPAM-HNP composite scaffolds were investigated for their potential as thermally triggered systems using a Q-switched Nd:YAG laser. These studies show that incorporation of HNPs resulted in scaffold deformation after very short irradiation times (seconds) due to internal structural heating. Our data highlights the potential of these hybrid-scaffold constructs for exploitation in drug delivery, using methylene blue as a model drug being released during remote structural change of the scaffold

Isospectral Mathieu-Hill Operators

In this paper we prove that the spectrum of the Mathieu-Hill Operators with potentials ae^{-i2{\pi}x}+be^{i2{\pi}x} and ce^{-i2{\pi}x}+de^{i2{\pi}x} are the same if and only if ab=cd, where a,b,c and d are complex numbers. This result implies some corollaries about the extension of Harrell-Avron-Simon formula. Moreover, we find explicit formulas for the eigenvalues and eigenfunctions of the t-periodic boundary value problem for the Hill operator with Gasymov's potential

Using audio for feedback on assessments: Tutor and student experiences

Recently we have been providing individual audio feedback to 1st and 2nd year undergraduate Chemistry students on a variety of assessments (posters, laboratory reports, laboratory diaries) with the aim of providing richer, more detailed and more comprehensible individual feedback than is possible within the same timeframe using written feedback. In this communication, various aspects of the use of audio for feedback are discussed including practical and technical aspects of the recording of audio files whilst viewing and assessing student work, the transmission of these files to individual students, our experiences as tutors of providing audio feedback and the experiences and views of students on audio feedback

What Shall We Do About The Organ

https://digitalcommons.acu.edu/crs_books/1585/thumbnail.jp

Identification by Disaggregation

Standard economic theory predicts that the actions of individual participants in competitive markets have negligible effects on market-determined aggregates. Applied researchers, and even some econometric textbooks, incorrectly infer from this that market prices can be modeled as econometrically exogenous with respect to the quantity demanded of an individual consumer. This faulty inference has even led some researchers (for example, Robert Engle, 1978; Nicholas Kiefer, 1984; Roger Waud, 1974) to employ an estimation strategy we call identification by disaggregation (IBD). This procedure attempts to circumvent the simultaneity problem in a macro regression by disaggregating the dependent variable and estimating the relationship for individual agents or sectors. This note provides a simple proof that estimates using disaggregated dependent variables suffer, on average, from the same degree of simultaneity bias as the estimates using aggregate data