Scattering matrices and affine Hecke algebras

We construct the scattering matrices for an arbitrary Weyl group in terms of elementary operators which obey the generalised Yang-Baxter equation. We use this construction to obtain the affine Hecke algebras. The center of the affine Hecke algebras coincides with commuting Hamiltonians. These Hamiltonians have q-deformed affine Lie algebras as symmetry algebra.Comment: 22 pages, harvmac, no figures, Lecture at Schladming, March 4,11 199

Vignette Equivalence and Response Consistency : The case of job satisfaction

Preprin

The chemical evolution of gas-rich dwarf galaxies

A numerical double burst model of the chemical evolution of gas-rich dwarf galaxies has been developed. The model is fitted to a sample of N/O, O/H, Y and gas fraction observations, where N/O and O/H are the relative abundances by number of nitrogen to oxygen and oxygen to hydrogen, respectively. Y is the abundance by mass of helium. Closed models as well as models including enriched outflow, ordinary outflow and ordinary outflow combined with inflow are considered.The bursts are assumed to be instantaneous but ordered in pairs to explain the scatter in N/O-O/H. The method of gas fraction fitting is revised, and it is found that it is very important to specify whether dwarf irregulars (dIrrs) or blue compact galaxies (BCGs) are considered. Effective enriched winds fail when fitting N/O, whereas closed models, models with ordinary winds or a combination of ordinary winds and inflow are all viable.Comment: 22 pages, 25 figures, MNRAS LaTeX forma

Tripartite entanglement in parametric down-conversion with spatially-structured pump

Most investigations of multipartite entanglement have been concerned with temporal modes of the electromagnetic field, and have neglected its spatial structure. We present a simple model which allows to generate tripartite entanglement between spatial modes by parametric down-conversion with two symmetrically-tilted plane waves serving as a pump. The characteristics of this entanglement are investigated. We also discuss the generalization of our scheme to 2N+1-partite entanglement using 2N symmetrically-tilted plane pump waves. Another interesting feature is the possibility of entanglement localization in just two spatial modes.Comment: 6 pages, 2 figure

Semirelativistic potential model for low-lying three-gluon glueballs

The three-gluon glueball states are studied with the generalization of a semirelativistic potential model giving good results for two-gluon glueballs. The Hamiltonian depends only on 3 parameters fixed on two-gluon glueball spectra: the strong coupling constant, the string tension, and a gluon size which removes singularities in the potential. The Casimir scaling determines the structure of the confinement. Low-lying $J^{PC}$ states are computed and compared with recent lattice calculations. A good agreement is found for $1^{--}$ and $3^{--}$ states, but our model predicts a $2^{--}$ state much higher in energy than the lattice result. The $0^{-+}$ mass is also computed.Comment: 2 figure

Image and Reality: the Case of Job Satisfaction

This study makes a distinction between two types of utility. Experienced utility is defined as the job satisfaction derived from the present job, estimated by using a subjective evaluation of job satisfaction. Anticipated utility is defined as the individual’s anticipated job satisfaction before starting the job and it is studied by using a stated preference methodology known as conjoint analysis. The results suggest that the two utility concepts are different. Information about experienced utility is useful for the evaluation of well-being policies and the welfare effects of various employer strategies. Anticipated utility provides knowledge about the job search process.European Commission, Fifth Framework Programme "Improving Human Potential" (contract number: HPSE-CT-2002-00143)

An Almost Integration-free Approach to Ordered Response Models

In this paper we propose an alternative approach to the estimation of ordered response models. We show that the Probit-method may be replaced by a simple OLS-approach, called P(robit)OLS, without any loss of efficiency. This method can be generalized to the analysis of panel data. For large-scale examples with random fixed effects we found that computing time was reduced from 90 minutes to less than one minute. Conceptually, the method removes the gap between traditional multivariate models and discrete variable modelsCategorical data; Ordered probit model; Ordered response models; Subjective data; Subjective well-being

Bridging the Gap between Farmers and Researchers through Collaborative Experimentation. Cost and Labour Reduction in Soybean Production in South-Nyanza, Kenya

The Tropical Soil Biology and Fertility Institute of the International Centre of Tropical Agriculture (TSBF-CIAT) introduced dual purpose soybean varieties in south-west Kenya both to improve soil fertility by nitrogen fixation and to provide a source of better food and income. Since the start of the project in 2005, the Uriri Farmer Cooperative Society was successful in spreading the seeds over the district. Nevertheless, farmers still had problems with soybean agronomy. We therefore started a Collaborative Experiment (CE) Approach in March 2006 to make soybean production more accessible to farmers. The approach consisted of four stages: 1) information sessions; 2) participatory rural appraisal; 3) collaboration in the whole process of experimentation, from problem identification, to the design and analysis; 4) handing over to farmers. In this case study, farmers identified two main constraints to the recommended soybean production methods: 1) high labour requirement 2) lack of income to purchase the inputs. The results and discussions with farmers during the field days allowed demonstrating that the CE approach had been successful on two main aspects. First, CE was successful in defining problems and yield enhancing treatments which are accessible to deprived people. During field days, all farmers felt there was at least one of the treatments accessible to them. The second main success of the CE process was the increased awareness and interest about soybean. After less than a year of collaboration, farmers saw that soybean can bring a better life, cash for school fees and better health. The number of farmers registered in the soybean cooperative also increased from a few hundreds to 4500 that year. Several farmers started their own experiments to further adapt the recommendations to their own needs. The CE approach was thus successful in bridging the power-relations and knowledge gap between researchers and farmers and in designing appropriate technologies.Collaborative research, soybean, participation, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

S\mathcal{S}-Matrix of Nonlocal Scalar Quantum Field Theory in the Representation of Basis Functions

Nonlocal quantum theory of one-component scalar field in $D$-dimensional Euclidean spacetime is studied in representations of $\mathcal{S}$-matrix theory for both polynomial and nonpolynomial interaction Lagrangians. The theory is formulated on coupling constant $g$ in the form of an infrared smooth function of argument $x$ for space without boundary. Nonlocality is given by evolution of Gaussian propagator for the local free theory with ultraviolet form factors depending on ultraviolet length parameter $l$. By representation of the $\mathcal{S}$-matrix in terms of abstract functional integral over primary scalar field, the $\mathcal{S}$ form of a grand canonical partition function is found. And, by expression of $\mathcal{S}$-matrix in terms of the partition function, the representation for $\mathcal{S}$ in terms of basis functions is obtained. Derivations are given for discrete case where basis functions are Hermite functions, and for continuous case where basis functions are trigonometric functions. The obtained expressions for the $\mathcal{S}$-matrix are investigated within the framework of variational principle based on Jensen inequality. Equations with separable kernels satisfied by variational function $q$ are found and solved, yielding results for both the polynomial theory $\varphi^{4}$ and the nonpolynomial sine-Gordon theory. A new definition of the $\mathcal{S}$-matrix is proposed to solve additional divergences which arise in application of Jensen inequality for the continuous case. Analytical results are illustrated numerically. For simplicity of numerical calculation: the $D=1$ case is considered, and propagator for the free theory $G$ is in the form of Gaussian function typically in the Virton-Quark model. The formulation for nonlocal QFT in momentum $k$ space of extra dimensions with subsequent compactification into physical spacetime is discussed.Comment: 38 pages, 18 figures; v2: significant text editing; v3: text and plots edited, references and acknowledgments added; prepared for the special issue of the journal Particles in memory of G.V. Efimo