Measurement of the Transverse Beam Spin Asymmetry in Elastic Electron Proton Scattering and the Inelastic Contribution to the Imaginary Part of the Two-Photon Exchange Amplitude

We report on a measurement of the asymmetry in the scattering of transversely polarized electrons off unpolarized protons, A$_\perp$, at two Q$^2$ values of \qsquaredaveragedlow (GeV/c)$^2$ and \qsquaredaveragedhighII (GeV/c)$^2$ and a scattering angle of $30^\circ < \theta_e < 40^\circ$. The measured transverse asymmetries are A$_{\perp}$(Q$^2$ = \qsquaredaveragedlow (GeV/c)$^2$) = (\experimentalasymmetry alulowcorr $\pm$ \statisticalerrorlow$_{\rm stat}$ $\pm$ \combinedsyspolerrorlowalucor$_{\rm sys}$) $\times$ 10$^{-6}$ and A$_{\perp}$(Q$^2$ = \qsquaredaveragedhighII (GeV/c)$^2$) = (\experimentalasymme tryaluhighcorr $\pm$ \statisticalerrorhigh$_{\rm stat}$ $\pm$ \combinedsyspolerrorhighalucor$_{\rm sys}$) $\times$ 10$^{-6}$. The first errors denotes the statistical error and the second the systematic uncertainties. A$_\perp$ arises from the imaginary part of the two-photon exchange amplitude and is zero in the one-photon exchange approximation. From comparison with theoretical estimates of A$_\perp$ we conclude that $\pi$N-intermediate states give a substantial contribution to the imaginary part of the two-photon amplitude. The contribution from the ground state proton to the imaginary part of the two-photon exchange can be neglected. There is no obvious reason why this should be different for the real part of the two-photon amplitude, which enters into the radiative corrections for the Rosenbluth separation measurements of the electric form factor of the proton.Comment: 4 figures, submitted to PRL on Oct.

Evidence for Strange Quark Contributions to the Nucleon's Form Factors at Q2Q^2 = 0.108 (GeV/c)2^2

We report on a measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized protons with the A4 apparatus at MAMI in Mainz at a four momentum transfer value of $Q^2$ = \Qsquare (GeV/c)$^2$ and at a forward electron scattering angle of 30$^\circ < \theta_e < 40^\circ$. The measured asymmetry is $A_{LR}(\vec{e}p)$ = (\Aphys $\pm$ \Deltastat$_{stat}$ $\pm$ \Deltasyst$_{syst}$) $\times$ 10$^{-6}$. The expectation from the Standard Model assuming no strangeness contribution to the vector current is A$_0$ = (\Azero $\pm$ \DeltaAzero) $\times$ 10$^{-6}$. We have improved the statistical accuracy by a factor of 3 as compared to our previous measurements at a higher $Q^2$. We have extracted the strangeness contribution to the electromagnetic form factors from our data to be $G_E^s$ + \FakGMs $G_M^s$ = \GEsGMs $\pm$ \DeltaGEsGMs at $Q^2$ = \Qsquare (GeV/c)$^2$. As in our previous measurement at higher momentum transfer for $G_E^s$ + 0.230 $G_M^s$, we again find the value for $G_E^s$ + \FakGMs $G_M^s$ to be positive, this time at an improved significance level of 2 $\sigma$.Comment: 4 pages, 3 figure

Progressive Focusing and Trustworthiness in Qualitative Research: The Enabling Role of Computer-Assisted Qualitative Data Analysis Software (CAQDAS)

* The business and management community increasingly recognises that qualitative research is a ‘messy’, non-linear and often unpredictable undertaking. Yet, a considerable proportion of the qualitative research published in top journals is still presented as the result of a linear, predictable research process, thus wrongly suggesting deductive reasoning. * In this paper, we focus on a particular type of ‘messiness’ where during fieldwork, the research context is revealed to be more complex than anticipated, forcing the researcher to gradually refine/shift their focus to reflect ‘what really matters’. We adopt Stake’s notion of progressive focusing for this gradual approach. * Progressive focusing is well-suited to qualitative research in international business requiring complex iteration between theory and data, and the truthful yet coherent presentation of the research process. We propose that this dual challenge of complexity and trustworthiness may be addressed by using computer-assisted qualitative data analysis software (CAQDAS). * We present conceptual considerations and guidelines and offer a view on a ‘messy’, non-linear doctoral research project conducted using a progressive focusing approach, to demonstrate how CAQDAS can help to develop and re-negotiate insights from theory and interview data, as well as enhance trustworthiness, transparency and publication potential

Beispiele zum Einfluss der Bildungsbedingungen auf Natürliche Mischkristallgleichgewichte

Der Artikel zeigt im ersten Beispiel den erheblichen Einfluss des Sauerstoffpartialdruckes auf die Mischkristallbeziehungen im System FeO-Fe₂O₃-Cr₂O₃, der trotz eines fixen Fe/Cr-Verhältnisses die Bildung davon erheblich abweichender Chromitphasen veranlassen kann. Im zweiten Beispiel wird gezeigt, dass die bisherigen experimentellen Mischkristalluntersuchungen im pseudobinären Sytem PbS-Bi₂S₃ keineswegs dazu angetan sind, zum Verständnis der Bildungsvorgänge der natürlichen Bleiwismutspiessglanzgruppe beizutragen, die obendrein wegen ihrer geringen Beimengungen von vorwiegend Cu, Fe, Ag und Sb gar nicht in diesem System dargestellt werden kann. Im dritten Beispiel wird darauf hingewiesen, dass bei der metamorphen Plagioklas-bildung fur deren temperaturabhängige Mischkristallzusammensetzung keineswegs nur das Stoffangebot des Gesamtgesteines ausschlaggebend ist. In vielen Fällen lassen sich zwischen der chemischen Zusammensetzung von Plagioklasen und unmittelbar benachbarten Hornblenden Beziehungen aufstellen. Dabei werden die Ca- und Al-, Na- und Si-Gehalte der beiden Phasen entsprechend den physikalisch-chemischen Reaktionsbedingungen ausgetauscht. Die Temperaturabhängigkeit dieser Zweiphasenreaktion darf jedoch auf keinen Fall mit dem experimentell ermittelten Plagioklas Thermometer verglichen werden.The article illustrates firstly, the extensive influence of the partial oxygen pressure on the solid solution relations in the system FeO-Fe₂O₃-Cr₂O₃ may, in spite of a fixed Fe/Cr ratio, influence the formation of chromite phases in such a way, that they deviate appreciably from the fixed ratio. Secondly, it is shown, that the hitherto experimentally investigated solid solutions in the pseudobinary system PbS-Bi₂S₃ do not contribute towards the understanding of the genesis of the natural lead-bismuth sulfosalts, because of the presence of small amount of Cu, Fe, Ag and Sb which cannot be represented in this system. Thirdly it is shown that, for the formation of metamorphic plagioclases, the temperature dependent solid solution compositions are not necessarily dependent on the total chemistry of the rock. In many examples it is possible to illustrate a relationship between the chemical composition of the plagioclase and the adjoining hornblende, in that the Ca-and Al-, Na-and Si-of these two phases are exchanged according to the prevailing physical-chemical reaction conditions. The temperature dependence of this two-phase reaction may, under no condition be compared to the experimentally determined plagioclase geothermometer.Cet article illustre premièrement, l'influence marquante de la pression partielle d'oxygène sur les domaines de solutions solides en système FeO-Fe₂O₃-Cr₂O₃. La pression partielle P[O₂] régnant dans un système de rapport Fe/Cr fixé peut agir sur la formation des phases du type chromite, pour faire s'écarter notablement leur composition de ce rapport. Deuxièmement, que les solutions solides jusqu'ici étudiées dans le système pseudobinaire PbS-Bi₂S₃ ne contribuent pas à la compréhension de la genèse des sulfosels plomb-bismuth naturels en raison des faibles quantités de Cu, Fe, Ag et Sb qui ne peuvent être représentés dans ce système. Troisièmement, on montre que la formation de plagioclases métamorphiques dont la composition est fonction de la température ne dépend pas nécessairement de la chimie de la roche totale. Dans de nombreux cas il est possible d'illustrer les relations entre les compositions des plagioclases et hornblendes coexistants. Le Ca, Al, Na et Si de ces deux phases s'échangent d'après les conditions physico-chimiques ambiantes. Les variations de température de cette réaction à deux phases ne peuvent en aucun cas être comparées au géothermomètre des plagioclases déterminé expérimentalement.Klemm D. D., Snethlage R., Weber-Diefenbach K. Beispiele zum Einfluss der Bildungsbedingungen auf Natürliche Mischkristallgleichgewichte. In: Bulletin de la Société française de Minéralogie et de Cristallographie, volume 97, 2-5, 1974. Les solutions solides en minéralogie. Colloque international du C.N.R.S. n° 234. 27-30 mai 1974, Orléans, France

Razao Sr:Ba:Rb e tipologia de zircao em granitoides dos Estado de Sao Paulo, Parana e Minas Gerais

Chemical (Sr:Ba:Rb) and zircon typology data from the Nazare Paulista, Mairipora/Cantareira, Cunhaporanga, Tres Corregos, Morungaba, Socorro, Itu, Graciosa and Serra Carambei granitoid complexes from the states of Minas Gerais, Sao Paulo and Parana (SE/S Brazil) are presented and discussed. By the zircon typology method these complexes are refered, respectively, to the 2nd crustal, 3rd crustal/low temperature C-A, low temperature C-A, medium temperature C-A, medium/light temperature C-A, K-SA/Alkaline and alkaline series which are considered as generated under increasing temperature associated with a progressive major participation of mantle material. All these series display different positions and behaviour in the Sr:Ba:Rb diagram which reinforces the use of the zircon typology method in the study of granitoids. -from English summar

Katastrophen-Monitoring am Beispiel Islands Schlussbericht

SIGLEAvailable from TIB Hannover: F02B387 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany)DEGerman

Ethnie und Migration

Diehm I. Ethnie und Migration. In: Coelen T, Otto H-U, eds. Grundbegriffe Ganztagsbildung. Das Handbuch. Wiesbaden: VS Verlag für Sozialwissenschaften; 2008: 98-105