Pre-main-sequence isochrones -- I. The Pleiades benchmark

We present a critical assessment of commonly used pre-main-sequence isochrones by comparing their predictions to a set of well-calibrated colour-magnitude diagrams of the Pleiades in the wavelength range 0.4 to 2.5 microns. Our analysis shows that for temperatures less than 4000 K the models systematically overestimate the flux by a factor two at 0.5 microns, though this decreases with wavelength, becoming negligible at 2.2 microns. In optical colours this will result in the ages for stars younger than 10 Myr being underestimated by factors between two and three. We show that using observations of standard stars to transform the data into a standard system can introduce significant errors in the positioning of pre-main-sequences in colour-magnitude diagrams. Therefore we have compared the models to the data in the natural photometric system in which the observations were taken. Thus we have constructed and tested a model of the system responses for the Wide-Field Camera on the Isaac Newton Telescope. As a benchmark test for the development of pre-main-sequence models we provide both our system responses and the Pleiades sequence.Comment: 15 pages, 12 figures, 7 tables, accepted for publication in MNRAS. All tables are available online at the Cluster Collaboration homepage http://www.astro.ex.ac.uk/people/timn/Catalogues

Matrix Selection for the Visualization of Small Molecules and Lipids in Brain Tumors Using Untargeted MALDI-TOF Mass Spectrometry Imaging

Matrix-assisted laser desorption/ionization mass spectrometry imaging allows for the study of metabolic activity in the tumor microenvironment of brain cancers. The detectable metabolites within these tumors are contingent upon the choice of matrix, deposition technique, and polarity setting. In this study, we compared the performance of three different matrices, two deposition techniques, and the use of positive and negative polarity in two different brain cancer types and across two species. Optimal combinations were confirmed by a comparative analysis of lipid and small-molecule abundance by using liquid chromatography–mass spectrometry and RNA sequencing to assess differential metabolites and enzymes between normal and tumor regions. Our findings indicate that in the tumor-bearing brain, the recrystallized α-cyano-4-hydroxycinnamic acid matrix with positive polarity offered superior performance for both detected metabolites and consistency with other techniques. Beyond these implications for brain cancer, our work establishes a workflow to identify optimal matrices for spatial metabolomics studies

Robuste Lagerungen. Grundlagen fuer die Entwicklung verbesserter, stoerungsunempfindlicher Lagerungen fuer hohe Umfangsgeschwindigkeiten Abschlussbericht

Robust sliding bearings with high circumferential speeds can be developed with modern software tools. The calculations are validated by measurements made on different types of bearings at circumferential speeds up to 125 m/s. With disturbance calculations and parameter variations made for characteristic types and sizes of bearings, the effects of deviations and secondary influences can be assessed, robust parameter ranges can be selected, and bearings can be optimized in advance, also with a view to oil supply and cooling. Clearince should be calculated in dependence of size and thermal deformation. In the case of tilted segment bearings with spherical supports, the enhanced tilting resistance may lead to instabilities. The project was successful. (orig.)Bei Gleitlagern mit hohen p x u-Werten koennen fertigungs-, montage-, betriebs- und verschleissbedingte Abweichungen von der Sollgeometrie des Schmierspalts, Drehbehinderungen und Verschraenkungen der Kippsegmente oder Zusatzeffekte bei schwimmenden Buechsen das Betriebsverhalten der Lager wesentlich beeinflussen. Mit dem erweiterten Gleitlagerprogramm ALP3T und den verbesserten Berechnungsgrundlagen fuer Kippsegment- und Schwimmbuechsenlager lassen sich die fuer die Entwicklung robuster Lager - hohe Umfangsgeschwindigkeiten durchfuehren. Die Zuverlaessigkeit der Rechenergebnisse wird ueber Vergleichsmessungen an sehr unterschiedlichen Lagerbauformen bei Umfangsgeschwindigkeiten bis zu 125 m/s nachgewiesen. Mit den fuer charakteristische Lagerbauformen und -groessen durchgefuehrten Stoerungsrechnungen und Parametervariationen lassen sich die Auswirkungen von Abweichungen und Zusatzeinfluessen bewerten, stoerungsunempfindliche Parameterbereiche auswaehlen und die Lager vorab (auch in der Olzufuehrung und Lagerkuehlung) weitgehend optimieren. Bei der Festlegung des Lagerspiels sind auch der Groesseneinfluss und die thermischen Verformungen zu beachten. Bei Kippsegmentlagern mit sphaerischer Abstuetzung kann der erhoehte Kippwiderstand zu einer Lagerinstabilitaet fuehren. Das Ziel des Forschungsvorhabens wurde erreicht. (orig.)Available from TIB Hannover: RA 1581(694) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEBundesministerium fuer Wirtschaft, Bonn (Germany); Arbeitsgemeinschaft Industrieller Forschungsvereinigungen e.V., Koeln (Germany)DEGerman

Tumor cell-derived spermidine promotes a pro-tumorigenic immune microenvironment in glioblastoma via CD8+ T cell inhibition

The glioblastoma microenvironment is enriched in immunosuppressive factors that potently interfere with the function of cytotoxic T lymphocytes. Cancer cells can directly impact the immune system, but the mechanisms driving these interactions are not completely clear. Here we demonstrate that the polyamine metabolite spermidine is elevated in the glioblastoma tumor microenvironment. Exogenous administration of spermidine drives tumor aggressiveness in an immune-dependent manner in pre-clinical mouse models via reduction of CD8+ T cell frequency and phenotype. Knockdown of ornithine decarboxylase, the rate-limiting enzyme in spermidine synthesis, did not impact cancer cell growth in vitro but did result in extended survival. Furthermore, glioblastoma patients with a more favorable outcome had a significant reduction in spermidine compared to patients with a poor prognosis. Our results demonstrate that spermidine functions as a cancer cell-derived metabolite that drives tumor progression by reducing CD8+T cell number and function