Exploratory electromagnetic thruster research, phase 3, 23 June - 23 December 1969

Performance evaluation of MPD arc jets operating in quasi-steady mode

Investigation of pulsed quasi-steady MPD arc jets

Evaluation of magnetohydrodynamic arc thrusters operating in quasi-steady mode with electrode vapor as propellan

A population-based case-control study on social factors and risk of testicular germ cell tumours

Objectives Incidence rates for testicular cancer have risen over the last few decades. Findings of an association between the risk of testicular cancer and social factors are controversial. The association of testicular cancer and different indicators of social factors were examined in this study.<p></p> Design Case–control study.<p></p> Setting Population-based multicentre study in four German regions (city states Bremen and Hamburg, the Saarland region and the city of Essen).<p></p> Participants The study included 797 control participants and 266 participants newly diagnosed with testicular cancer of which 167 cases were classified as seminoma and 99 as non-seminoma. The age of study participants ranged from 15 to 69 years.<p></p> Methods Social position was classified by educational attainment level, posteducational training, occupational sectors according to Erikson-Goldthorpe-Portocarrero (EGP) and the socioeconomic status (SES) on the basis of the International SocioEconomic Index of occupational status (ISEI). ORs and corresponding 95% CIs (95% CIs) were calculated for the whole study sample and for seminoma and non-seminoma separately.<p></p> Results Testicular cancer risk was modestly increased among participants with an apprenticeship (OR=1.7 (95% CI 1.0 to 2.8)) or a university degree (OR=1.6 (95% CI 0.9 to 2.8)) relative to those whose education was limited to school. Analysis of occupational sectors revealed an excess risk for farmers and farm-related occupations. No clear trend was observed for the analyses according to the ISEI-scale.<p></p> Conclusions Social factors based on occupational measures were not a risk factor for testicular cancer in this study. The elevated risk in farmers and farm-related occupations warrants further research including analysis of occupational exposures.<p></p&gt

Static and dynamic Jahn-Teller effect in the alkali metal fulleride salts A4C60 (A = K, Rb, Cs)

We report the temperature dependent mid- and near-infrared spectra of K4C60, Rb4C60 and Cs4C60. The splitting of the vibrational and electronic transitions indicates a molecular symmetry change of C604- which brings the fulleride anion from D2h to either a D3d or a D5d distortion. In contrast to Cs4C60, low temperature neutron diffraction measurements did not reveal a structural phase transition in either K4C60 and Rb4C60. This proves that the molecular transition is driven by the molecular Jahn-Teller effect, which overrides the distorting potential field of the surrounding cations at high temperature. In K4C60 and Rb4C60 we suggest a transition from a static to a dynamic Jahn-Teller state without changing the average structure. We studied the librations of these two fullerides by temperature dependent inelastic neutron scattering and conclude that both pseudorotation and jump reorientation are present in the dynamic Jahn-Teller state.Comment: 13 pages, 10 figures, to be published in Phys. Rev.

Otto Müller’s Surirella taxa (Bacillariophyta) from East Africa, based on a Historical Collection kept at the Botanic Garden and Botanical Museum Berlin-Dahlem

At the beginning of the 20th century, Otto Müller described over 100 new freshwater diatom taxa from algae samples, collected during the German “Nyassa-See– und Kinga-Gebirgs-Expedition” in East Africa. He published valuable drawings and wrote detailed descriptions of these microalgae, but subsequent authors regarded many of these African taxa to be synonyms or infraspecific of European species. In the last two decades renewed attention to the diatom flora of East Africa has made it evident that Müller’s taxa have to be reinvestigated, in terms of both light as well as scanning electron microscopy, in order to evaluate possible new or endemic species. This was recently done for his Surirella taxa, a typical component of the African Great Lakes diatom flora of which many species are endemic to this area. Additional data, originating from material of later periods in the same region (e.g. Lakes Tanganyika, Malawi, Victoria, Edward), was incorporated in the investigation to study the variability in valve morphology and the African distribution of each species. Otto Müller’s samples thus provide the means to study historical African diatom diversity as a baseline for modern biodiversity assessment. Type information and the English description for taxon have been published in international journals and online at the AlgaTerra Information System [www.algaterra.org], a site developed and updated by the Botanic Garden and Botanical Museum Berlin-Dahlem (BGBM). High resolution digital photographs of the Surirella taxa will also be available in the future on the API website [www.aluka.org]

Instantons and Monopoles in General Abelian Gauges

A relation between the total instanton number and the quantum-numbers of magnetic monopoles that arise in general Abelian gauges in SU(2) Yang-Mills theory is established. The instanton number is expressed as the sum of the `twists' of all monopoles, where the twist is related to a generalized Hopf invariant. The origin of a stronger relation between instantons and monopoles in the Polyakov gauge is discussed.Comment: 28 pages, 8 figures; comments added to put work into proper contex

The Path Integral for 1+1-dimensional QCD

We derive a path integral expression for the transition amplitude in 1+1-dimensional QCD starting from canonically quantized QCD. Gauge fixing after quantization leads to a formulation in terms of gauge invariant but curvilinear variables. Remainders of the curved space are Jacobians, an effective potential, and sign factors just as for the problem of a particle in a box. Based on this result we derive a Faddeev-Popov like expression for the transition amplitude avoiding standard infinities that are caused by integrations over gauge equivalent configurations.Comment: 16 pages, LaTeX, 3 PostScript figures, uses epsf.st

Peritumoral administration of GPI-anchored TIMP-1 inhibits colon carcinoma growth in Rag-2 gamma chain-deficient mice

Exogenous application of recombinant TIMP-1 protein modified by addition of a glycosylphosphatidylinositol (GPI) anchor allows efficient insertion of the fusion protein into cell membranes. This `cell surface engineering' leads to changes in the proteolytic environment. TIMP-1-GPI shows enhanced as well as novel in vitro biological activities including suppression of proliferation, reduced migration, and inhibition of invasion of the colon carcinoma cell line SW480. Treatment of SW480 tumors implanted in Rag (-/-) common gamma chain (-/-) C57BL/6 mice with peritumorally applied TIMP-1-GPI, control rhTIMP-1 protein, or vehicle shows that TIMP-1-GPI leads to a significant reduction in tumor growth

Jahreszeitliche Schwankungen und Einfluss der Ernährung auf die makuläre Pigmentdichte

Zusammenfassung: Hintergrund: Wir haben gezeigt, dass die makuläre Pigmentdichte (MPD) mit einem modifizierten konfokalen Scanning-Laser-Ophthalmoskop (HRA, Fa. Heidelberg Engineering, Heidelberg, Deutschland) bestimmt werden kann. In dieser Studie untersuchten wir, ob Schwankungen der MPD bei gesunden Probanden im Verlauf eines Jahres auftraten und ob die MPD von wechselnden Ernährungsgewohnheiten abhängig ist. Methode: Die MPD wurde mithilfe von Autofluoreszenzbildern, die mit einem HRA aufgenommen wurden, dargestellt und in einem auf die Fovea zentrierten Messfeld von 2° Durchmesser bei den Probanden im Abstand von 2Monaten innerhalb eines Jahres bestimmt. Ergebnisse: Wir schlossen 30 gesunde Probanden im Alter von 19-34Jahren (Mittel: 23±2Jahre) in die Studie ein. Die mittlere MPD war an Untersuchungszeitpunkt1 0,215±0,056D.U., bei der 2.Untersuchung 0,235±0,051D.U., bei der 3. 0,218±0,055D.U., an Untersuchungszeitpunkt4 0,228±057D.U., bei der 5.Untersuchung 0,225±0,053D.U. und bei der letzten 0,203±0,050D.U.. Die statistische Analyse zeigte keine signifikanten Unterschiede der MPD im Verlauf eines Jahres. Zusammenfassung: Die Studie zeigt, dass bei jungen und gesunden Probanden die MPD keinen jahreszeitlichen und diätetischen Schwankungen unterlieg