Measuring velocity ratios with correlation functions

We show how to determine the ratio of the transverse velocity of a source to the velocity of emitted particles, using split-bin correlation functions. The technique is to measure $S_2$ and $S_2^{\phi}$, subtract the contributions from the single-particle distribution, and take the ratio as the bin size goes to zero. We demonstrate the technique for two cases: each source decays into two particles, and each source emits a large number of particles.Comment: 9 pages, LaTeX, 2 PostScript figure

The high-frequency finite-temperature quark dispersion relation

I calculate the dispersion relation for quarks of mass $m$ and momentum $k$ in a quark gluon plasma at temperature $T$, in the limit $m^2+k^2 \gg (gT)^2$, where $g$ is the strong coupling constant. I find three contributions to the dispersion relation: one that depends on $T$ but not $m$ or $k$, one that depends on $m$ and $T$ but not $k$, and third contribution that depends on all three (and is opposite in sign to the other two).Comment: latex, 5 pages, CERN-TH.7034/9

Social Interaction and R & D Project Performance

[Excerpt] The purpose of this working paper is to present some initial findings from research currently being conducted on the effect of informal structures of communication and interaction on the product development process. The general hypothesis of the study is that higher levels of communication are associated with more effective working relationships among the different functional groups working on product innovation. The first part of this paper will review previous work in the area. Part II develops the questions of the current study. Part III outlines the methods used to address the research questions. Part IV presents the results from an initial pilot study performed within one organization. The final section discusses these results in terms of their implications for the management of innovation

Analysis techniques for high-multiplicity collisions

I discuss methods for identifying and quantifying phase transitions in particle collisions, concentrating on two techniques for use in ultra-relativistic nuclear collisions. The first technique is to use rapidity correlation measurements to determine the correlation length, while the second is to use the transverse mass distribution of dileptons in the rho-omega peak to determine the transition temperature.Comment: 5 pages (latex), preprint CERN-TH.6771/93. Proceedings of the XXIst International Workshop on Gross Properties of Nuclei and Nuclear Excitations, Hirschegg, Kleinwalsertal, Austria, January 1993 (GSI, Darmstadt, 1993; H. Feldmeier, ed.

Correlation measurements in high-multiplicity events

Requirements for correlation measurements in high--multiplicity events are discussed. Attention is focussed on detection of so--called hot spots, two--particle rapidity correlations, two--particle momentum correlations (for quantum interferometry) and higher--order correlations. The signal--to--noise ratio may become large in the high--multiplicity limit, allowing meaningful single--event measurements, only if the correlations are due to collective behavior.Comment: MN 55455, 20 pages, KSUCNR-011-92 and TPI-MINN-92/47-T (revised). Revised to correct typo in equation (30), and to fill in a few steps in calculations. Now published as Phys. Rev. C 47 (1993) 232

Thermal photon production in high-energy nuclear collisions

We use a boost-invariant one-dimensional (cylindrically symmetric) fluid dynamics code to calculate thermal photon production in the central rapidity region of S+Au and Pb+Pb collisions at SPS energy ($\sqrt{s}=20$ GeV/nucleon). We assume that the hot matter is in thermal equilibrium throughout the expansion, but consider deviations from chemical equilibrium in the high temperature (deconfined) phase. We use equations of state with a first-order phase transition between a massless pion gas and quark gluon plasma, with transition temperatures in the range $150 \leq T_c \leq 200$ MeV.Comment: revised, now includes a_1 contribution. revtex, 10 pages plus 4 figures (uuencoded postscript

On the dialog between experimentalist and modeler in catchment hydrology

The dialog between experimentalist and modeler in catchment hydrology has been minimal to date. The experimentalist often has a highly detailed yet highly qualitative understanding of dominant runoff processes—thus there is often much more information content on the catchment than we use for calibration of a model. While modelers often appreciate the need for 'hard data' for the model calibration process, there has been little thought given to how modelers might access this 'soft' or process knowledge. We present a new method where soft data (i.e., qualitative knowledge from the experimentalist that cannot be used directly as exact numbers) are made useful through fuzzy measures of model-simulation and parameter-value acceptability. We developed a three-box lumped conceptual model for the Maimai catchment in New Zealand, a particularly well-studied process-hydrological research catchment. The boxes represent the key hydrological reservoirs that are known to have distinct groundwater dynamics, isotopic composition and solute chemistry. The model was calibrated against hard data (runoff and groundwater-levels) as well as a number of criteria derived from the soft data (e.g. percent new water, reservoir volume, etc). We achieved very good fits for the three-box model when optimizing the parameter values with only runoff (Reff=0.93). However, parameter sets obtained in this way showed in general a poor goodness-of-fit for other criteria such as the simulated new-water contributions to peak runoff. Inclusion of soft-data criteria in the model calibration process resulted in lower Reff-values (around 0.84 when including all criteria) but led to better overall performance, as interpreted by the experimentalist’s view of catchment runoff dynamics. The model performance with respect to soft data (like, for instance, the new water ratio) increased significantly and parameter uncertainty was reduced by 60% on average with the introduction of the soft data multi-criteria calibration. We argue that accepting lower model efficiencies for runoff is 'worth it' if one can develop a more 'real' model of catchment behavior. The use of soft data is an approach to formalize this exchange between experimentalist and modeler and to more fully utilize the information content from experimental catchments

Labour market outcomes after vocational training in Germany : equal opportunities for migrants and natives?

"German in-firm vocational training combines training on the job and learning in vocational schools. The so called 'dual system' absorbs roughly two thirds of German school leavers every year. After between two and four years of standardized training, it provides them with a generally accepted qualification in a wide range of occupations. Using Spence's Signaling Theory, hypotheses are derived concerning different labour market outcomes of foreigners who successfully completed an in-firm vocational training course and their German counterparts. The integration potential of the dual system is tested empirically according to its risk factors unemployment, occupational mismatch and skill mismatch using longitudinal registration data (1977-2004). Different nationalities are compared with Germans with respect to their first employment after leaving the dual system. Today, most of the young migrants who go through the dual system are as successful on the labour market as Germans. In-firm vocational training apparently provides migrant youth with the skills and techniques necessary for a successful transition to the labour market. However, they have restricted transition chances due to having higher unemployment rates, occupational mismatch and skill mismatch. But even if we control for relevant variables that determine transition chances, restrictions at labour market entry still remain for individual nationalities: compared to Germans, migrant men and especially migrant women have a higher risk of unemployment and occupational mismatch." (Author's abstract, IAB-Doku) ((en)) Additional Information Hier finden Sie eine deutschsprachige Kurzfassung des Beitrags.Jugendliche, ausländische Jugendliche, Berufseinmündung, betriebliche Berufsausbildung, Arbeitsmarktchancen, Ausbildungsabsolventen