How Good are Present Analytical QCD-Predictions on Fluctuations in Angular Intervals ?

Results on two-particle angular correlations in jet cones and on multiplicity fluctuations in one- and two- dimensional angular intervals, delivered by three experiments (DELPHI, L3 and ZEUS, at $\sqrt{s}$ from few to 183 GeV) are compared to present existing analytical QCD calculations, using the LPHD hypothesis. Two different types of functions have been tested. While the differentially normalized correlation functions show substantial deviations from the predictions, a globally normalized correlation function agrees surprisingly well. The role of the QCD parameters $\alpha_s$, $\Lambda$ and $n_f$ is discussed. The necessity to include full energy-momentum conservation into the analytical calculations is stressed.Comment: 13 pages (LaTeX), 11 figures, uses sprocl.sty. Miniraporteur-talk given at the Internat. Symposium of Multiparticle Dynamics, Delphi, Greece, 6-11 Sept. 1998 (to appear in Proceedings

Study of gluon fragmentation and colour octet neutralization in DELPHI

Using the full statistics of the DELPHI experiment at $\sqrt{s}=91 GeV$ 3-jet events are selected and gluon respectively quark jet enriched subsamples are defined. The leading systems of the two kinds of jets are determined using rapidity gaps. The sum of charges of the leading systems is studied. It is found that for gluon-jets there is a significant excess of leading systems with total charge zero when compared to Monte Carlo simulations with JETSET. The corresponding leading systems of quark-jets do not exhibit such an excess. The mass spectra of the leading systems with total charge zero are studied.Comment: 8 pages, 6 figures (in eps) talk given at XXXI International Symposium on Multiparticle Dynamics, Sep. 1-7, 2001, Datong China URL http://ismd31.ccnu.edu.cn

Conceptual and socio-cognitive support for collaborative learning in videoconferencing environments

Studies have shown that videoconferences are an effective medium for facilitating communication between parties who are separated by distance. Furthermore, studies reveal that videoconferences are effective when used for distance learning, particularly when learners are engaged in complex collaborative learning tasks. However, as in face-to-face communication, learners benefit most when they receive additional support for such learning tasks. This article provides an overview of three empirical studies to illustrate more general insights regarding some of the more and less effective ways of supporting collaborative learning with videoconferencing. The focus is on conceptual support, such as structural visualization and socio-cognitive support, such as scripts. Based on the results of the three studies, conclusions can be drawn about the conceptual and socio-cognitive support measures that promote learning. Conclusions can also be reached about the need for employing both conceptual and socio-cognitive support to provide learners with the most benefit

Two-center resonant photo ionization

Photoionization of an atom $A$, in the presence of a neighboring atom $B$, can proceed via resonant excitation of $B$ with subsequent energy transfer to $A$ through two-center electron-electron correlation. We demonstrate that this two-center mechanism can strongly outperform direct photoionization at nanometer internuclear distances and possesses characteristic features in its time development and the spectrum of emitted electrons.Comment: 4 pages, 3 figure

Investigation of Bose-Einstein Correlations in 3 jet events with the DELPHI detector

A preliminary investigation of Bose-Einstein correlations in 3 jet events has been made by analysing the collected data at the $Z^0$ peak from '94 and '95 and the calibration runs during the LEP2 period from '97 to 2000. Three methods were used to extract two-particle correlation functions. No significant difference was found between quark and gluon jets for all three methods.Comment: 6 pages, 2 figures in ps and 1 in eps, talk given at XXXI International Symposium on Multiparticle Dynamics, Sept 1-7, 2001, Datong China. see http://ismd31.ccnu.edu.cn

The s-wave pion-nucleus optical potential

We calculate the s-wave part of the pion-nucleus optical potential using a unitarized chiral approach that has been previously used to simultaneously describe pionic hydrogen and deuterium data as well as low energy pi N scattering in the vacuum. This energy dependent model allows for additional isoscalar parts in the potential from multiple rescattering. We consider Pauli blocking and pion polarization in an asymmetric nuclear matter environment. Also, higher order corrections of the pi N amplitude are included. The model can accommodate the repulsion required by phenomenological fits, though the theoretical uncertainties are bigger than previously thought. At the same time, we also find an enhancement of the isovector part compatible with empirical determinations.Comment: 31 pages, 27 figure

An iOS Framework for the Indivo X Personally Controlled Health Record

The Indivo X personally controlled health record creates a channel between researchers and the patient/subject in several large scale projects. Indivo enables patients to access their health data through a web interface and, as an “apps platform”, can be extended in functionality. Patient-facing apps, such as a medication list, may improve the data flow between researcher and patient, in both directions, and as such provide better data for the researcher and immediate benefit for the patient. However, research projects in general do not allocate large funds to patient facing apps, let alone a mobile interface. Thus we have created a framework that greatly simplifies connecting an iOS app to an Indivo X server. Our open-source framework enables novel as well as experienced iOS developers to build mobile interfaces for their research subjects, taking advantage of Indivo X

A description of the f2(1270), rho3(1690), f4(2050), rho5(2350) and f6(2510) resonances as multi-rho(770) states

In a previous work regarding the interaction of two $\rho(770)$ resonances, the $f_2(1270)$ ($J^{PC}=2^{++}$) resonance was obtained dynamically as a two-$\rho$ molecule with a very strong binding energy, 135~MeV per $\rho$ particle. In the present work we use the $\rho\rho$ interaction in spin 2 and isospin 0 channel to show that the resonances $\rho_3(1690)$ ($3^{--}$), $f_4(2050)$ ($4^{++}$), $\rho_5(2350)$ ($5^{--}$) and $f_6(2510)$ ($6^{++}$) are basically molecules of increasing number of $\rho(770)$ particles. We use the fixed center approximation of the Faddeev equations to write the multi-body interaction in terms of the two-body scattering amplitudes. We find the masses of the states very close to the experimental values and we get an increasing value of the binding energy per $\rho$ as the number of $\rho$ mesons is increased.Comment: 17 pages, 6 figure

Langevin Trajectories between Fixed Concentrations

We consider the trajectories of particles diffusing between two infinite baths of fixed concentrations connected by a channel, e.g. a protein channel of a biological membrane. The steady state influx and efflux of Langevin trajectories at the boundaries of a finite volume containing the channel and parts of the two baths is replicated by termination of outgoing trajectories and injection according to a residual phase space density. We present a simulation scheme that maintains averaged fixed concentrations without creating spurious boundary layers, consistent with the assumed physics

Aktuelle theoretische Ansätze und empirische Befunde im Bereich der Lehr-Lern-Forschung:Schwerpunkt Erwachsenenbildung

Das Gutachten dient dem im Jahr 2004 vom DIE ins Leben gerufenen „Expertenkreis Lehre in der Weiterbildung“ als Arbeitsgrundlage. Es stellt die aktuellen Ansätze und Befunde im Bereich des Lehrens und Lernens mit Schwerpunkt auf der Erwachsenenbildung dar. Neuere Ansätze zum Lehren und Lernen aus der Empirischen Pädagogik und Pädagogischen Psychologie werden vorgestellt und auf spezifische Aspekte der Weiterbildung wie Communities, berufliche Weiterbildung und Blended Learning eingegangen. Die verschiedenen Ebenen, Aufgabenfelder und Phasen des Bildungsmanagements werden beleuchtet und das Bildungscontrolling näher erläutert. Danach folgen Ausführungen zu einem mitarbeiterorientierten Implementationsmodell innovativer Lehr-Lern-Ansätze in Organisationen. Anhand der vorgestellten Ansätze und Befunde des Lehrens und Lernens werden Folgerungen für die Forschung und für die Ausund Weiterbildung der Lehrenden im Bereich der Erwachsenenbildung gezogen