The Library and Remedial/Developmental/Compensatory Education: A Case Study

published or submitted for publicatio

Modelling of the fast rotating delta Scuti star Altair

We present an asteroseismic study of the fast rotating star HD187642 (Altair), recently discovered to be a delta Scuti pulsator. We have computed models taking into account rotation for increasing rotational velocities. We investigate the relation between the fundamental radial mode and the first overtone in the framework of Petersen diagrams. The effects of rotation on such diagrams, which become important at rotational velocities above 150 km/s, as well as the domain of validity of our seismic tools are discussed. We also investigate the radial and non-radial modes in order to constrain models fitting the five most dominant observed oscillation modes.Comment: Accepted for publication in A&A (11 pages, 6 figures, 4 tables

The role of rotation on Petersen Diagrams. The Pi1/0(Omega) Pi_{1/0}(Omega) period ratios

The present work explores the theoretical effects of rotation in calculating the period ratios of double-mode radial pulsating stars with special emphasis on high-amplitude delta Scuti stars (HADS). Diagrams showing these period ratios vs. periods of the fundamental radial mode have been employed as a good tracer of non-solar metallicities and are known as Petersen diagrams (PD).In this paper we consider the effect of moderate rotation on both evolutionary models and oscillation frequencies and we show that such effects cannot be completely neglected as it has been done until now. In particular it is found that even for low-to-moderate rotational velocities (15-50 km/s), differences in period ratios of some hundredths can be found. The main consequence is therefore the confusion scenario generated when trying to fit the metallicity of a given star using this diagram without a previous knowledge of its rotational velocity.Comment: A&A in pres

Student Conceptual Difficulties in Hydrodynamics

We describe a study on the conceptual difficulties faced by college students in understanding hydrodynamics of ideal fluids. This study was based on responses obtained in hundreds of written exams and oral interviews, which were held with first-year Engineering and Science university students. Their responses allowed us to identify a series of misconceptions unreported in the literature so far. The study findings demonstrate that the most important difficulties arise from the students' inability to establish a link between the kinematics and dynamics of moving fluids, and from a lack of understanding regarding how different regions of a system interact.Comment: 12 pages, 10 figures (small corrections

Recent high resolution laboratory determinations of line broadening and intensity parameters: PH3, CH3D, and CO2

Recent unpublished laboratory work on rovibrational line strengths and broadening coefficients which is of interest in the study of planetary atmospheres was reviewed. The molecules discussed are PH3, CH3D and CO2

Toroidal Carbon Nanotubes with Encapsulated Atomic Metal Loops

Toroidal carbon nanotubes can serve as hosts for encapsulated loops of atomic metal wires. Such composite structures have been analyzed using density functional theory for a semiconducting C$_{120}$ torus encapsulating chains of Fe, Au and Cu atoms. The sheathed metal necklaces form a zigzag structure and drops the HOMO/LUMO bandgap to less than 0.1 eV. The iron composite is ferromagnetic with a magnetic moment essentially the same as that of bcc iron. The azimuthal symmetry of these toroidal composites suggests that they may offer novel elecromagnetic properties not associated with straight, metal-encapsulated carbon nanotubes.Comment: 6 pages, 9 figure

Local-global neural networks: a new approach for nonlinear time series modelling

In this paper, the Local Global Neural Networks model is proposed within the context of time series models. This formulation encompasses some already existing nonlinear models and also admits the Mixture of Experts approach. We place emphasis on the linear expert case and extensively discuss the theoretical aspects of the model: stationarity conditions, existence, consistency and asymptotic normality of the parameter estimates, and model identifiability. A model building strategy is also considered and the whole procedure is illustrated with two real time-series.neural networks, nonlinear models, time-series, model identifiability, parameter estimation, model building, sunspot number.

MODELING FARM AND OFF-FARM ECONOMIC LINKAGES TO ANALYZE THE IMPACTS OF AN AREA-WIDE INSECT MANAGEMENT PROGRAM ON A REGIONAL ECONOMY

This study evaluated the impacts of the boll weevil eradication program at the farm level and on the west Tennessee region. Budgets, an acreage response model, and an input-output model were used to evaluate direct and indirect program impacts. The program generates small but positive economic benefits for the region.Crop Production/Industries,