Kaon photoproduction: background contributions, form factors and missing resonances

The photoproduction p(gamma, K+)Lambda process is studied within a field-theoretic approach. It is shown that the background contributions constitute an important part of the reaction dynamics. We compare predictions obtained with three plausible techniques for dealing with these background contributions. It appears that the extracted resonance parameters drastically depend on the applied technique. We investigate the implications of the corrections to the functional form of the hadronic form factor in the contact term, recently suggested by Davidson and Workman (Phys. Rev. C 63, 025210). The role of background contributions and hadronic form factors for the identification of the quantum numbers of ``missing'' resonances is discussed.Comment: 11 pages, 7 eps figures, submitted to Phys. Rev.

Factors affecting hotel selection: Greek customers' perception

Selection of hotel is of high priority and significance for tourists and entails a complicated decision-making process. The paper aims at identifying the most significant hotel selection factors taken into account by Greek customers. An empirical research study was conducted using an online survey. Ten factors identified by literature review included in the investigation. The findings indicate that Cleanliness is the most important factor in the selection of accommodation, followed by Price and Staff. Considering the priorities of tourists, hotel managers may design more effectively their segmentation, targeting and positioning strategy to ensure that their offerings match the needs and wants of their guests

Factors affecting hotel selection: Greek customers' perception

Selection of hotel is of high priority and significance for tourists and entails a complicated decision-making process. The paper aims at identifying the most significant hotel selection factors taken into account by Greek customers. An empirical research study was conducted using an online survey. Ten factors identified by literature review included in the investigation. The findings indicate that Cleanliness is the most important factor in the selection of accommodation, followed by Price and Staff. Considering the priorities of tourists, hotel managers may design more effectively their segmentation, targeting and positioning strategy to ensure that their offerings match the needs and wants of their guests

The S11−NS_{11}- N(1535) and −N-N(1650) Resonances in Meson-Baryon Unitarized Coupled Channel Chiral Perturbation Theory

The $s-$wave meson-baryon scattering is analyzed for the strangeness S=0 sector in a Bethe-Salpeter coupled channel formalism incorporating Chiral Symmetry. Four channels have been considered: $\pi N$, $\eta N$, $K \Lambda$, $K \Sigma$. The needed two particle irreducible matrix amplitude is taken from lowest order Chiral Perturbation Theory in a relativistic formalism and low energy constants are fitted to the elastic $\pi N$ phase-shifts and the $\pi^- p \to \eta n$ and $\pi^- p \to K^0 \Lambda$ cross section data. The position of the complex poles in the second Riemann sheet of the scattering amplitude determine masses and widths of the $S_{11}-$ $N$(1535) and $-N$(1650) resonances, in reasonable agreement with experiment. A good overall description of data, from $\pi N$ threshold up to 2 GeV, is achieved keeping in mind that the two pion production channel has not been included.Comment: 35 pages, LaTeX + 7 ps-figure files. Some minor mistakes have been corrected for and a new appendix discussing the matching to HBChPT has been also adde

Analyzing Powers for pp → pnπ^+

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Model dependence of single-energy fits to pion photoproduction data

Model dependence of multipole analysis has been explored through energy-dependent and single-energy fits to pion photoproduction data. The MAID energy-dependent solution has been used as input for an event generator producing realistic pseudo data. These were fitted using the SAID parametrization approach to determine single-energy and energy-dependent solutions over a range of lab photon energies from 200 to 1200 MeV. The resulting solutions were found to be consistent with the input amplitudes from MAID. Fits with a $\chi$-squared per datum of unity or less were generally achieved. We discuss energy regions where consistent results are expected, and explore the sensitivity of fits to the number of included single- and double-polarization observables. The influence of Watson's theorem is examined in detail.Comment: 12 pages, 8 figure

Mapping and identification of candidate loci responsible for Peromyscus hybrid overgrowth

Crosses between two recently diverged rodent species of the genus Peromyscus result in dramatic parent-of-origin effects on growth and development. P. maniculatus females crossed with P. polionotus males yield growth-retarded conceptuses, whereas the reciprocal cross results in overgrowth and lethality. These hybrid effects are particularly pronounced in the placenta. We previously detected linkage to two regions of the genome involved in the overgrowth effects. One locus, termed Peal, is a paternally expressed autosomal locus mapping to a domain whose house mouse equivalent contains several clusters of imprinted genes. The other locus, termed Mexl, maps to a gene-poor region of the X chromosome. Here we use an advanced intercross line to verify and narrow the regions of linkage and identify candidate genes for Mexl and Peal. While we have previously shown that Mexl affects both pre-and postnatal growth, we show here that Peal affects only prenatal growth. Utilizing criteria such as mutant phenotypes and allelic expression, we identify the loci encoding the homeobox protein Esx1 and the zinc-finger protein Pw1/Peg3 as candidates. Both loci exhibit expression changes in the hybrids

Differentiation of primary, secondary and tertiary aromatic amines in fossil fuels using trifluoroacylation

An analytical method which distinguishes between primary, secondary and tertiary amines has been developed. Trifluoroacetic anhydride, with 4-pyrrolidinopyridine as a catalyst, is used to form di- and mono-trifluoroacylated derivatives of primary and secondary aromatic amines, respectively. Tertiary aromatic amines such as quinoline do not react. GC/MS is then used to analyze the derivatized samples. Retention indices and response factors (relative to 4-fluoroaniline) are reported for >50 pure compounds known or expected to be present in fossil fuel base fractions. Also, results from the analysis of base fractions from mildly hydrotreated SRC II coal liquids and petroleum-derived light cycle oils will be reported