More on the Narrowing of Impact Broadened Radio Recombination Lines at High Principal Quantum Number

Recently Alexander and Gulyaev have suggested that the apparent decrease in impact broadening of radio recombination lines seen at high principal quantum number n may be a product of the data reduction process, possibly resulting from the presence of noise on the telescope spectra that is not present on the calculated comparison spectra. This is an interesting proposal. However, there are serious problems with their analysis that need to be pointed out. Perhaps the most important of these is the fact that for principal quantum numbers below n = 200, where the widths are not in question, their processed generated profile widths do not fit the widths of the processed lines obtained at the telescope. After processing, the halfwidths of the generated and telescope profiles must agree below n = 200 if we are to believe that the processed generated linewidths above n = 200 are meaningful. Theirs do not. Furthermore, we find that after applying the linewidth reduction factors found by Alexander and Gulyaev for their noise added profiles to our generated profiles to simulate their noise adding effect, the processed widths we obtain still do not come close to explaining the narrowing seen in the telescope lines for n values in the range 200 < n < 250. It is concluded that what is needed to solve this mystery is a completely new approach using a different observing technique instead of simply a further manipulation of the frequency-switched data.Comment: Six pages with 4 figures. Accepted for publication in Astrophysics and Space Scienc

Sensitive Observations of Radio Recombination Lines in Orion and W51: The Data and Detection of Systematic Recombination Line Blueshifts Proportional to Impact Broadening

Sensitive spectral observations made in two frequency bands near 6.0 and 17.6 GHz are described for Orion and W51. Using frequency switching we were able to achieve a dynamic range in excess of 10,000 without fitting sinusoidal or polynomial baselines. This enabled us to detect lines as weak as T$_{A} ~1mK in these strong continuum sources. Hydrogen recombination lines with$\Delta n$ as high as 25 have been detected in Orion. In the Orion data, where the lines are stronger, we have also detected a systematic shift in the line center frequencies proportional to linewidth that cannot be explained by normal optical depth effects.Comment: 22 pages, 13 figures. Accepted for publication in Astrophysics and Space Scienc

Hydrogen and helium line formation in OB dwarfs and giants. A hybrid non-LTE approach

Aims: Hydrogen and helium line spectra are crucial diagnostic features for the quantitative analysis of OB stars. We compute synthetic spectra based on a hybrid non-LTE approach in order to test the ability of these models to reproduce high-resolution and high-S/N spectra of dwarf and giant stars and also to compare them with published grids of non-LTE (OSTAR2002) and LTE (Padova) models. Methods: Our approach solves the restricted non-LTE problem based on classical line-blanketed LTE model atmospheres. State-of-the-art model atoms and line-broadening theories are employed to model the H and He I/II spectra over the entire optical range and in the near-IR. Results: The synthetic spectra match almost all measurable hydrogen and helium lines observed in six test stars over a wide spectral range from the Balmer limit to the NIR, except for only a few well-understood cases. Our approach reproduces other published non-LTE calculations, however avoids inconsistencies with the modelling of the He I singlets recently discussed in the literature. It improves on the published LTE models in many aspects: non-LTE strengthening and the use of improved line-broadening data result in overall significant differences in the line profiles and equivalent widths of the Balmer and helium lines. Where possible, systematic effects on the stellar parameter determination are quantified, e.g. gravities derived from the Hgamma wings may be overestimated by up to ~0.2 dex at our upper temperature boundary in LTE. (abridged)Comment: 25 pages, 19 figures. Modified according to suggestions of the referee. Accepted for publication in A&A. Several figures in low resolution. A high-resolution pdf version of the preprint can be downloaded from http://www.sternwarte.uni-erlangen.de/~ai97/preprints/HHe_nieva.pd

Insolation and gacial meltwater influence on sea‐ice and circulation variability in the Northeastern Labrador Sea during the last glacial period

The variable amounts of ice rafted debris (IRD) and foraminifers in North Atlantic sediments are related to the abrupt, millennial-scale alteration from Greenland stadials to interstadials during the last glacial period and indicate past ice sheet instabilities, changes in sea-ice cover and productivity. In the Norwegian Sea, Greenland stadials were likely characterized by an extensive, near-perennial sea-ice cover whereas Greenland interstadials were seasonally ice-free. The variability in other areas, such as the Labrador Sea, remains, however, obscure. We therefore investigated deep-sea sediment core GS16-204-22CC retrieved south of Greenland. Using a multiproxy approach, we distinguish two sediment regimes and hence different environmental conditions between ca. 65 and 25 ka b2k. Regime 1 (similar to 65-49 ka b2k) is characterized by the dominance of planktic foraminifers in the sediments. During late MIS4 and early MIS3, the site was covered by near-perennial sea-ice with occasional periods of iceberg discharge. During the younger part of regime 1 the northeastern Labrador Sea was seasonally ice-free with hardly any icebergs melting near the site and long-term environmental conditions were less variable. Regime 2 (similar to 49-25 ka b2k) is characterized by pronounced stadial-interstadial variability of foraminifer and IRD fluxes, suggesting an extensive sea-ice cover during most Greenland stadials and seasonally ice-free conditions during most Greenland interstadials. During MIS2 environmental conditions were very similar to those of the younger part of regime 1. While all Heinrich (H) related Greenland stadials are marked by depleted oxygen isotope values at our core site, only H4 and H3 are associated with pronounced IRD peaks. Plain Language Summary North Atlantic sediments contain variable amounts of sand-sized mineral grains and microorganism shells. Mineral grains indicate iceberg transport from continental ice sheets, like the Greenland ice sheet (more icebergs/melting sea-ice, more grains). If the sea-ice cover is too thick, no light can penetrate and fewer microorganisms live in the water beneath the ice. Using these indicators, we investigated ocean sediments from south of Greenland covering the time period between ca. 65 and 25 thousand years ago. This time period was characterized by several abrupt changes between cold and warm climates on millennial timescales. We find that the ocean south of Greenland was sea-ice covered for most of the year with occasional time periods of iceberg discharge between 65 to 56 thousand years ago. From 56 to 49 thousand years ago the ice-free season was extended and hardly any icebergs melted near the site. From 49 thousand years ago our study area was covered by sea-ice year-round during cold time intervals whereas warm time intervals were only seasonally sea-ice covered. Continental ice sheets were growing during this time interval and we observed two major calving events related to two of the four very cold climate intervals recorded in the analyzed sediment.Fundacao de a Ciencia e a Tecnologia IF/01500/2014 UID/Multi/04326/2019info:eu-repo/semantics/publishedVersio

Das Krankenhaus, Basel II und der Investitionsstau

Die vorliegende Studie untersucht die zukünftige Entwicklung der Finanzierungskosten von Krankenhäusern vor dem Hintergrund (i) des anhaltenden Rückzugs der öffentlichen Hand aus der Finanzierung von Investitionen und des dadurch entstandenen Investitionsstaus und (ii) der von Banken im Gefolge von Basel II verstärkt geforderten Risiko sensitiven Zinsmargen. Der Schwerpunkt der Untersuchung liegt auf dem Kreditbedarf, der entsteht, um den Herausforderungen im Krankenhaussektor gerecht werden zu können. Statistische Grundlage bilden öffentlich vorliegende Geschäftsberichte. Substanzielle Unterschiede in den Bilanzen und den Gewinn- und Verlustrechnungen erfordern fü die Analyse eine Unterteilung der Krankenhäuser in private und nicht-private. Wir kommen zu dem Ergebnis, dass sich das derzeitige Kreditvolumen (ohne KHG-Fördermittel) auf etwa 10 Mrd. Euro beläuft und die jährlichen Finanzierungskosten auf ca. 500 Mill. Euro. Vor dem Hintergrund der schlechten wirtschaftlichen Situation vieler Krankenhäuser und des wachsenden Wettbewerbsdrucks mit der Einführung des neuen Abrechnungssystems (DRG Fallpauschalen) seit Januar 2004 erwarten wir höhere Ausfallwahrscheinlichkeiten - vor allem bei öffentlichen Krankenhäusern, für die die bürgenden Kommunen aus eigener finanzieller Schwäche immer weniger die Haftung übernehmen können. Bis 2010 dürfte die Anzahl der Krankenhäuser von heute über 2 200 auf etwa 1 900 zurückgehen. Mittelfristig erwarten wir daher im Gefolge von Basel II höhere Risikomargen im Krankenhaussektor, die zu etwa 170 Mill. Euro Mehrkosten führen dürften. Ferner gehen wir davon aus, dass die steigende Wettbewerbsintensität den Druck zum Abbau des Investitionsstaus erhöht, gleichzeitig aber der Rückzug der öffentlichen Hand aus der Investitionsfinanzierung anhält. Dies führt zu rund 1,36 Mrd. Euro zusätzlichen Finanzierungskosten, sodass insgesamt 1,53 Mrd. Euro Zusatz- bzw. 2 Mrd. Euro Gesamtkosten entstehen

Dynamic and Stagnating Plasma Flow Leading to Magnetic Flux Tube Collimation

Highly collimated, plasma-filled magnetic flux tubes are frequently observed on galactic, stellar and laboratory scales. We propose that a single, universal magnetohydrodynamic pumping process explains why such collimated, plasma-filled magnetic flux tubes are ubiquitous. Experimental evidence from carefully diagnosed laboratory simulations of astrophysical jets confirms this assertion and is reported here. The magnetohydrodynamic process pumps plasma into a magnetic flux tube and the stagnation of the resulting flow causes this flux tube to become collimated.Comment: to be published in PRL; color figures on electronic versio

Quantum-mechanical calculation of Stark widths of Ne VII n=3, Δn=0\Delta n=0 transitions

The Stark widths of the Ne VII 2s3s-2s3p singlet and triplet lines are calculated in the impact approximation using quantum-mechanical Convergent Close-Coupling and Coulomb-Born-Exchange approximations. It is shown that the contribution from inelastic collisions to the line widths exceeds the elastic width contribution by about an order of magnitude. Comparison with the line widths measured in a hot dense plasma of a gas-liner pinch indicates a significant difference which may be naturally explained by non-thermal Doppler effects from persistent implosion velocities or turbulence developed during the pinch implosion. Contributions to the line width from different partial waves and types of interactions are discussed as well.Comment: 8 pages, 3 figures; accepted by Phys. Rev.

Scattering polarization of hydrogen lines in the presence of turbulent electric fields

We study the broadband polarization of hydrogen lines produced by scattering of radiation, in the presence of isotropic electric fields. In this paper, we focus on two distinct problems: a) the possibility of detecting the presence of turbulent electric fields by polarimetric methods, and b) the influence of such fields on the polarization due to a macroscopic, deterministic magnetic field. We found that isotropic electric fields decrease the degree of linear polarization in the scattered radiation, with respect to the zero-field case. On the other hand, a distribution of isotropic electric fields superimposed onto a deterministic magnetic field can generate a significant increase of the degree of magnetic-induced, net circular polarization. This phenomenon has important implications for the diagnostics of magnetic fields in plasmas using hydrogen lines, because of the ubiquitous presence of the Holtsmark, microscopic electric field from neighbouring ions. In particular, previous solar magnetographic studies of the Balmer lines of hydrogen may need to be revised because they neglected the effect of turbulent electric fields on the polarization signals. In this work, we give explicit results for the Lyman-alpha and Balmer-alpha lines.Comment: 15 pages, 6 figure

Strukturreformen im deutschen Gesundheitswesen

Die vorliegende Studie ist das Ergebnis eines gemeinsamen Projektes der ADMED GmbH und des RWI. Ziel ist die Darstellung wesentlicher Ineffizienzen im deutschen Gesundheitswesen. Zur Beurteilung ihrer Bedeutung erfolgt eine grobe Abschätzung der damit verbundenen Einsparpotenziale, wobei es sich um reine Wirtschaftlichkeitsreserven handelt, Investitionskosten werden nicht mit einbezogen. Die Berechnungen basieren entweder auf Fallerfahrung der ADMED GmbH oder auf aggregierten Daten auf volkswirtschaftlicher Ebene. Bei mangelhafter Datenlage wurden konservative Annahmen getroffen. Zur fundierten mikroökonomischen Verifikation der Abschätzungen sind weiter gehende Untersuchungen und insbesondere eine Verbesserung der Datenlage im Gesundheitswesen erforderlich. Die untersuchten Kostensenkungsmaßnahmen beziehen sich nur auf folgende Felder: Primär- und Sekundärleistungen von Leistungserbringern und Fragen der Systemregulierung. Die Behebung von Ineffizienzen bei Leistungserbringern würde zu Einsparungen in der Größenordnung von mindestens 7,5 bis 10 Mrd. Euro pro Jahr führen, womit die GKV-Beiträge um bis zu 0,7 bis 0,9 %- Punkte gesenkt werden könnten. Zum Teil handelt es sich um Potenziale, die schon bei den heutigen gesetzlichen Rahmenbedingungen gehoben werden könnten. Hierzu bedarf es allerdings einer konsequenten Umsetzung einzelner Vorschläge. Andere Potenziale können erst in Betracht gezogen werden, wenn die Politik entsprechende Voraussetzungen dafür schafft. Die Umsetzung selbst ist nicht trivial und erfordert eine konsequente Umsetzungsplanung. Über diese Überlegungen hinaus gehende Untersuchungen zu Fehlanreizen im System weisen auf ein weiteres, möglicherweise beachtliches Einsparpotenzial hin. Der Mangel an empirischen Untersuchungen hierzu verdeutlicht den dringend notwendigen Bedarf an fundierten wissenschaftlichen Evaluationsstudien auf dem Gebiet der Gesundheitsökonomie

Stark Broadening of the B III 2s-2p Lines

We present a quantum-mechanical calculation of Stark line widths from electron-ion collisions for the $2s_{1/2}-2p_{1/2,3/2}$, lambda = 2066 and 2067 A, resonance transitions in B III. The results confirm the previous quantum-mechanical R-matrix calculations but contradict recent measurements and semi-classical and some semi-empirical calculations. The differences between the calculations can be attributed to the dominance of small L partial waves in the electron-atom scattering, while the large Stark widths inferred from the measurements would be substantially reduced if allowance is made for hydrodynamic turbulence from high Reynolds number flows and the associated Doppler broadening.Comment: 21 pages, 4 figures; to be published in Phys. Rev.