Comment on ``Bethe Ansatz Results for the 4f-Electron Spectra of a Degenerate Anderson Model ''

In a recent letter, Zvyagin calculates the density of states for 4f electrons coupled to a conduction band in the framework of the Bethe ansatz (BA) solution for the degenerate Anderson model. It is claimed that the results qualitatively disagree with the results obtained for the same model but using a variational approach. Even the high energy feature in the f-spectral function near the 4f-level energy ef, i.e. the ``normal'' ionization peak (NIP), is argued to be qualitatively different in the two approaches. In the following we point out that this is not the case.Comment: 1 page, RevTeX, no figur

Lathe attachment used to machine elliptical cones

Close-tolerance elliptical cones are fabricated by cutting-tool guide assembly used with conventional tracer cartridge on turret lathe accurately produced in two machine operations

Apparatus for machining geometric cones Patent

Rotary spindle lathe attachments for machining geometrical cone

Attendance and Exam Performance at University

Marburger (2006) explored the link between absenteeism and exam performance by assessing the impact on absenteeism of removing a university wide policy of mandatory attendance for a single class. His results indicate that while an attendance policy has a strong impact on reducing absenteeism the link between absenteeism and exam performance is weak.This paper presents an alternative exploration into the link between absenteeism and exam performance by assessing the impact of implementing a module-specific attendance policy. Our results suggest the link between absenteeism and exam performance is strong, and that student-specific factors are important, including revision strategies and peer group effects. These results question the uniformity of the relationship between attendance and exam performance.absenteeism, attendance, exam performance, undergraduate, peer groups

Matrix isolation technique for the study of some factors affecting the partitioning of trace elements

The factors that affect the preferred positions of cations in ionic solid solutions were investigated utilizing vibrational spectroscopy. Solid solutions of the sulfate and chromate ions codoped with La(+3) and Ca(+2) in a KBr host lattice were examined as a function of the polyvalent cation concentration. The cation-anion pairing process was found to be random for Ca(+2), whereas the formation of La(+3)-SO4(-2) ion pairs with a C2 sub v bonding geometry is highly preferential to any type of La(+3)-CrO4(-2) ion pair formation. The relative populations of ion pair site configurations are discussed in terms of an energy-entropy competition model which can be applied to the partition of trace elements during magmatic processes

Environmental Kuznets Curves: Mess or Meaning?

The shape of the relationship between the rate of environmental degradation and income per capita has been the subject of much empirical examination. When test results based around this so-called ‘environmental Kuznets curve’ are compared, the empirical evidence is neither consistently supportive of its traditional inverted-U shape nor uniform across pollutants. A deeper understanding of the characteristics of pollutants and of the derived demand and derived supply of pollutants needs to be achieved if environmental Kuznets curves are to be useful.Environmental Kuznets Curves, Empirical Evidence

Phonon spectral function for an interacting electron-phonon system

Using exact diagonalzation techniques, we study a model of interacting electrons and phonons. The spectral width of the phonons is found to be reduced as the Coulomb interaction U is increased. For a system with two modes per site, we find a transfer of coupling strength from the upper to the lower mode. This transfer is reduced as U is increased. These results give a qualitative explanation of differences between Raman and photoemission estimates of the electron-phonon coupling constants for A3C60 (A= K, Rb).Comment: 4 pages, RevTeX, 2 eps figur

Quantitative multielement analysis using high energy particle bombardment

Charged particles ranging in energy from 0.8 to 4.0 MeV are used to induce resonant nuclear reactions, Coulomb excitation (gamma X-rays), and X-ray emission in both thick and thin targets. Quantitative analysis is possible for elements from Li to Pb in complex environmental samples, although the matrix can severely reduce the sensitivity. It is necessary to use a comparator technique for the gamma-rays, while for X-rays an internal standard can be used. A USGS standard rock is analyzed for a total of 28 elements. Water samples can be analyzed either by nebulizing the sample doped with Cs or Y onto a thin formvar film or by extracting the sample (with or without an internal standard) onto ion exchange resin which is pressed into a pellet

Convergence across Spanish Provinces:Cross-section and Pairwise Evidence

Distribution free statistics are employed to investigate biennial income per capita convergence across 52 Spanish provinces over the period 1955-1997. Based upon ideas of concordance and discordance that capture convergence and divergence properties, the paper presents results that suggest convergence is dominant for the full sample over the entire period, swings in this trend between convergence and divergence are present and switching in rank does take place. When provinces are analysed in pairs some show strong evidence of divergence.Convergence; Steady state; Average UK regional male wages

The optimal P3M algorithm for computing electrostatic energies in periodic systems

We optimize Hockney and Eastwood's Particle-Particle Particle-Mesh (P3M) algorithm to achieve maximal accuracy in the electrostatic energies (instead of forces) in 3D periodic charged systems. To this end we construct an optimal influence function that minimizes the RMS errors in the energies. As a by-product we derive a new real-space cut-off correction term, give a transparent derivation of the systematic errors in terms of Madelung energies, and provide an accurate analytical estimate for the RMS error of the energies. This error estimate is a useful indicator of the accuracy of the computed energies, and allows an easy and precise determination of the optimal values of the various parameters in the algorithm (Ewald splitting parameter, mesh size and charge assignment order).Comment: 31 pages, 3 figure