Spin current cross-correlations as a probe of magnon coherence

Motivated by the important role of the normalized second order coherence function, often called $g^{(2)}$, in the field of quantum optics, we propose a method to determine magnon coherence in solid-state devices. Namely, we show that the cross-correlations of pure spin-currents injected by a ferromagnet into two metal leads, normalized by their dc value, replicate the behavior of $g^{(2)}$ when magnons are driven far from equilibrium. We consider two scenarios: driving by ferromagnetic resonance, which leads to the coherent occupation of a single mode, and driving by heating of the magnons, which leads to an excess of incoherent magnons. We find an enhanced normalized cross-correlation in the latter case, thereby demonstrating bunching of nonequilibrium thermal magnons due to their bosonic statistics. Our results contribute to the burgeoning field of quantum magnonics, which seeks to explore and exploit the quantum nature of magnons

Was tun Lehrlinge nach ihrer Ausbildung? : eine Analyse mit dem Linked Employer-Employee-Datensatz des IAB (What do apprentices do after their training? : an analysis using the IAB Linked Employer-Employee dataset)

"The transition of western German apprentices at the end of their training is examined on the basis of a combined multiple choice and selection model. It models simultaneously a number of decisions made by the apprentices who have finished their training, as well as potentially existing internal and external wage offers depending on their characteristics. The analysis is carried out using the IAB Linked Employer-Employee dataset. The following results of the analysis are to be underlined: the level of the wage offer has a direct influence on an apprentice's decision to remain in the company where he/she has done his apprenticeship. In addition, a self-selection takes place of those apprentices who can obtain higher wages than expected either by staying in their company or by changing to another one. Thus, an efficient wage policy of the training company is possible in order to keep its apprentices after the training. Company-specific human capital plays a wage-increasing role both in the company's decision to make a wage offer as well as in the level of this wage offer. Wages below the market level which are based on the training company's insider-knowledge about the former apprentice's skills but which cannot be signalled to other companies (so-called wage compression) do not generally occur according to our results. Wage compression only happens in the case of apprentices who do not have an attractive offer immediately on completion of their training, and who therefore have to find a job on the open labour market. Thus, in Germany, training apprentices is obviously such a strong signal that it is not attractive for companies to use wage compression if they want to keep up with external wage offers for the good candidates." (Author's abstract, IAB-Doku) ((en))Ausbildungsabsolventen, betriebliche Berufsausbildung, beruflicher Verbleib - Determinanten, Lohnhöhe, zwischenbetriebliche Mobilität, IAB-Linked-Employer-Employee-Datensatz

Lokale Arbeitsmärkte für ausländische Arbeitskräfte in Deutschland : berufliche Veränderungsprozesse am Beispiel dreier idealtypischer Arbeitsmarktregionen (Local labour markets for foreign workers in Germany : occupational processes of change, taking as an example three ideal-typical labour market regions)

"This article examines the extent to which the structure of foreign workers in three different types of local labour market adapted to the respective structure of indigenous workers between 1980 and 1990. The Ruhr district is examined as an example of a traditional industrial region, Frankfurt as an example of a service region and Stuttgart as an example of 'high-tech production' and quality production in engineering. The report takes as a starting point the thesis that the patterns of employment of the foreign workers is gradually adapting to the demand pattern of the labour markets. Corresponding alignment processes are expected to take place more quickly in regions with a low rate of unemployment. Accordingly foreigners should be employed as skilled workers more often in Stuttgart than in the Ruhr district and more foreigners should be found in the services sector in Frankfurt. The analyses of the IAB employment sample, however, do not confirm these assumptions overall. Although a higher proportion of foreign workers can be found in services in the Frankfurt region, in Stuttgart foreign workers are employed disproportionately often as unskilled or semi-skilled workers, and in the Ruhr district on the other hand foreign workers can be found increasingly in skilled worker positions. In the Ruhr district less favourable working conditions, lower wages and less secure employment prospects even in qualified employment fields have led to them being unattractive for indigenous workers. The gaps arising in these employment fields have been filled by foreign workers." (Author's abstract, IAB-Doku) ((en))ausländische Arbeitnehmer - Struktur, Beschäftigtenstatistik, Beschäftigtenstruktur, Stellung im Beruf, regionale Mobilität, regionaler Arbeitsmarkt, sektorale Verteilung, berufliche Mobilität, Ruhrgebiet, Nordrhein-Westfalen, Frankfurt/Main, Hessen, Stuttgart, Baden-Württemberg, Bundesrepublik Deutschland

On voxel-by-voxel accumulated dose for prostate radiation therapy using deformable image registration.

Since delivered dose is rarely the same with planned, we calculated the delivered total dose to ten prostate radiotherapy patients treated with rectal balloons using deformable dose accumulation (DDA) and compared it with the planned dose. The patients were treated with TomoTherapy using two rectal balloon designs: five patients had the Radiadyne balloon (balloon A), and five patients had the EZ-EM balloon (balloon B). Prostate and rectal wall contours were outlined on each pre-treatment MVCT for all patients. Delivered fractional doses were calculated using the MVCT taken immediately prior to delivery. Dose grids were accumulated to the last MVCT using DDA tools in Pinnacle3 TM (v9.100, Philips Radiation Oncology Systems, Fitchburg, USA). Delivered total doses were compared with planned doses using prostate and rectal wall DVHs. The rectal NTCP was calculated based on total delivered and planned doses for all patients using the Lyman model. For 8/10 patients, the rectal wall NTCP calculated using the delivered total dose was less than planned, with seven patients showing a decrease of more than 5% in NTCP. For 2/10 patients studied, the rectal wall NTCP calculated using total delivered dose was 2% higher than planned. This study indicates that for patients receiving hypofractionated radiotherapy for prostate cancer with a rectal balloon, total delivered doses to prostate is similar with planned while delivered dose to rectal walls may be significantly different from planned doses. 8/10 patients show significant correlation between rectal balloon anterior-posterior positions and some VD values

Le hip-hop au Kenya : créateur d’identité ou nouvelle « musique nationale ». L’exemple d’« Unbwogable » de GidiGidiMajiMaji

Né en 1946, a fondé en 1991 les Archives de musique africaine dans le cadre de l’Institut d’études africaines et d’ethnologie de l’Université Johannes Gutenberg à Mayence (Allemagne). Il a étudié l’histoire du highlife nigérian, ainsi que, en vue de son habilitation en 1998, la praise culture qui fait l’objet d’un ouvrage actuellement en préparation. Un autre ouvrage, intitulé Sweet Mother. Modern African Music, publié originellement en 1985 (rééd. 2000), existe aussi en traductions anglaise (1991) et française (1992). Ses recherches portent avant tout sur l’histoire des enregistrements commerciaux et de la culture populaire en Afrique. Il est le rédacteur du site web consacré aux musiques et aux cultures populaires africaines. Partout en Afrique, le hip-hop a trouvé sa place sur la scène de la musique populaire. En même temps, un débat est né sur la question de savoir dans quelle mesure le hip-hop peut être considéré comme une musique africaine. Au Kenya, une chanson de rap est devenue l’hymne de l’opposition pendant la campagne électorale de 2002 qui a sonné le glas de la dictature de Daniel Arap Moi. L’auteur présente et analyse cette chanson. Dans le cas présent, le hip-hop en tant que musique globalisée a renforcé l’opposition luo – du moins initialement. Mais au cours de la campagne électorale, la chanson « Unbwogable » a fini par exprimer le sentiment de toute la nation. De cette manière, le hip-hop est devenu un genre généralement accepté, sans pour autant se muer en une « musique nationale »

Improved initial data for black hole binaries by asymptotic matching of post-Newtonian and perturbed black hole solutions

We construct approximate initial data for non-spinning black hole binary systems by asymptotically matching the 4-metrics of two tidally perturbed Schwarzschild solutions in isotropic coordinates to a resummed post-Newtonian 4-metric in ADMTT coordinates. The specific matching procedure used here closely follows the calculation in gr-qc/0503011, and is performed in the so called buffer zone where both the post-Newtonian and the perturbed Schwarzschild approximations hold. The result is that both metrics agree in the buffer zone, up to the errors in the approximations. However, since isotropic coordinates are very similar to ADMTT coordinates, matching yields better results than in the previous calculation, where harmonic coordinates were used for the post-Newtonian 4-metric. In particular, not only does matching improve in the buffer zone, but due to the similarity between ADMTT and isotropic coordinates the two metrics are also close to each other near the black hole horizons. With the help of a transition function we also obtain a global smooth 4-metric which has errors on the order of the error introduced by the more accurate of the two approximations we match. This global smoothed out 4-metric is obtained in ADMTT coordinates which are not horizon penetrating. In addition, we construct a further coordinate transformation that takes the 4-metric from global ADMTT coordinates to new coordinates which are similar to Kerr-Schild coordinates near each black hole, but which remain ADMTT further away from the black holes. These new coordinates are horizon penetrating and lead, for example, to a lapse which is everywhere positive on the t=0 slice. Such coordinates may be more useful in numerical simulations.Comment: 25 pages, 21 figures. Replaced with accepted versio

Nationalitäten- und geschlechtsspezifische Arbeitsmarktchancen von Absolventen der dualen Ausbildung

"Das duale Ausbildungssystem spielt eine wichtige Rolle für den Zugang zu besseren Arbeitsmarktsegmenten sowohl am Anfang der Erwerbskarriere als auch in der weiteren beruflichen Karriere. Für Ausländer sind im Inland erworbene Ausbildungszertifikate eine wichtige Zugangsvoraussetzung zu qualifizierten Beschäftigungsbereichen. Die hier vorliegende Analyse mit der anonymisierten lAB-Beschäftigtenstichprobe untersucht Arbeitsmarktchancen von Absolventinnen und Absolventen der dualen Ausbildung aus Spanien, Portugal, Italien, Griechenland, Türkei und dem ehemaligen Jugoslawien. Mittels Ereignisanalysen (Piecewise Constant Exponential Model) wird untersucht, ob Ausländer nach Abschluß einer dualen Ausbildung vergleichbare Arbeitsmarktchancen wie deutsche Absolventen haben. In den Analysen werden drei Übergänge unterschieden: der unmittelbar Berufswechsel, der Übergang von sozialversicherungspflichtiger Beschäftigung in Leistungsbezug (z.B. Bezug von Arbeitslosengeld) und der Übergang in eine Unterbrechung der sozialversicherungspflichtige Beschäftigung. Es sind bei den Absolventinnen und Absolventen der dualen Ausbildung weitestgehend nur Unterschiede zwischen Deutschen und Ausländern beim Wechsel in Unterbrechungen der sozialversicherungspflichtigen Erwerbsunterbrechung - nicht jedoch in Leistungsbezug bzw. im unmittelbaren Berufswechsel - feststellbar. Vergleicht man die Ergebnisse von Frauen und Männern, so zeigen sich keine wesentlichen Unterschiede der Wirkungszusammenhänge in den drei Übergangsformen. Somit bieten die Analysen viele Anhaltspunkte dafür, daß der berufliche Erfolg von Ausländern wesentlich von deren Bildungsgrad abhängt." (Autorenreferat