Estimating economic impact using ex post econometric analysis: Cautionary tales

This paper provides an overview of techniques that can be used to estimate the economic impact of stadiums, events, championships, and franchises on local economies. Utilizing data from National Collegiate Athletic Association championships, this paper highlights the potential problems that can be made if city and time effects are not handled and unit-roots are not accounted for. In addition, the paper describes the technique for estimating dynamic panel data and the advantages that come with these modeling techniques.College sports, impact analysis, econometrics

Retrospective analysis of suspicious non palpable breast lesions from : the initial years of the Breast Unit in Malta

Aim: The aim of this retrospective study was to analyse the false positive rate of suspicious non palpable breast lesions detected by ultrasonography and mommography. Method: the data was collected from the first seven years (2000-2007) since the set up of the Breast Unit in Malta. Results: The results showed that the false positive rate for suspicious breast lesions detected by ultrasound and mammography were 84% and 57.6% respectively. The overall false positive rate was 62.5%. Conclusion: The overall false positive rate for suspicious breast lesions detected by both radiographic modalities is high in our unit when compared to that of other countries. Suggestions for improvement are discussed.peer-reviewe

An Interface between the Universal Force Field and the Effective Fragment Potential Method

In order to properly describe reactions in heterogeneous catalyst systems, the reactants, solvent, and bulk effects of the surface must be taken into account. Embedded-cluster QM (quantum mechanics)/MM (molecular mechanics) methods can treat reactions on surfaces (the gas−surface interface), and the effective fragment potential method (EFP) can accurately treat the solvent effects on reactions (the gas−liquid interface). In order to create a QM/MM/EFP hybrid method for treatment of heterogeneous catalytic systems in the presence of a solvent (the liquid−surface interface), an EFP−MM interaction potential has been developed. Example calculations on small clusters of silica and water have been carried out

Comparison of Nitroaldol Reaction Mechanisms Using Accurate Ab Initio Calculations

In the nitroaldol reaction, condensation between a nitroalkane and an aldehyde yields a nitroalcohol that can undergo dehydration to yield a nitroalkene. Amine-functionalized, MCM-41-type mesoporous silica nanosphere (MSN) materials have been shown to selectively catalyze this reaction. Gas-phase reaction paths for the several competing mechanisms for the nitroaldol reaction have been mapped out using second-order perturbation theory (MP2). Improved relative energies were determined using singles and doubles coupled cluster theory with perturbative triples, CCSD(T). The mechanism in the absence of a catalyst was used to provide a baseline against which to assess the impact of the catalyst on both the mechanism and the related energetics. Catalyzed mechanisms can either pass through a nitroalcohol intermediate as in the classical mechanism or an imine intermediate

Ediacara biota flourished in oligotrophic and bacterially dominated marine environments across Baltica.

Middle-to-late Ediacaran (575-541 Ma) marine sedimentary rocks record the first appearance of macroscopic, multicellular body fossils, yet little is known about the environments and food sources that sustained this enigmatic fauna. Here, we perform a lipid biomarker and stable isotope (δ15Ntotal and δ13CTOC) investigation of exceptionally immature late Ediacaran strata (<560 Ma) from multiple locations across Baltica. Our results show that the biomarker assemblages encompass an exceptionally wide range of hopane/sterane ratios (1.6-119), which is a broad measure of bacterial/eukaryotic source organism inputs. These include some unusually high hopane/sterane ratios (22-119), particularly during the peak in diversity and abundance of the Ediacara biota. A high contribution of bacteria to the overall low productivity may have bolstered a microbial loop, locally sustaining dissolved organic matter as an important organic nutrient. These oligotrophic, shallow-marine conditions extended over hundreds of kilometers across Baltica and persisted for more than 10 million years

Two-photon decay of the singlet and triplet metastable states of helium-like ions

The two-photon decay rates and photon energy distributions of the metastable 2S1 and 2S3 states of the helium isoelectronic sequence are calculated by variational procedures for the ions He i through Ne ix. © 1969 The American Physical Society

Nonadiabatic long-range forces

A general expression is obtained for the leading long-range correction to the static interaction of a slowly moving charged or neutral system at a large distance from a spherically symmetric atom, and precise estimates are presented of the magnitude for the systems H, HeA (1S1,2S1,A and A 2S3), Ne, Ar, Kr, Xe, Li+A (1S1,2S1,A and A 2S3), Li, Na, K, Rb, Cs, H2, N2, and CH4. © 1968 The American Physical Society