Die Effizienz der Humboldtschen Universität – Eine empirische Analyse über Verbundeffekte und organisationale Unterschiedlichkeit im deutschen Hochschulwesen

Das Humboldtsche Organisationsideal betont die Bedeutung der Vielseitigkeit für den Erfolg von Hochschulen. Nach diesem Ideal sollte eine Hochschule thematisch alle Disziplinen der Wissenschaft unter einem organisationalen Dach vereinen und funktional sowohl in der Lehre als auch in der Forschung aktiv sein. Die ökonomische Perspektive hinterfragt diesen organisationalen Alleskönner. Sie stellt ihm die produktivitätssteigernde Bedeutung der Spezialisierung entgegen, nach der sich eine Hochschule vor allem auf einzelne Spitzenbereiche fokussieren sollte. Diese Dissertation beschäftigt sich mit der vermeintlichen Kollision der beiden Prinzipien. Zunächst betrachtet die Arbeit sowohl die innere als auch die äußere Unterschiedlichkeit von deutschen Hochschulen aus einer deskriptiven Perspektive. Zur Untersuchung der äußeren Unterschiedlichkeit wird in dieser Arbeit eine umfassende Klassifizierung der Hochschullandschaft erstellt, mithilfe derer verschiedene latente Hochschultypen im deutschen Hochschulsystem identifiziert werden können. Die innere Unterschiedlichkeit wird hingegen mit einer indexbasierten Analyse untersucht, die die Entwicklung der programmatischen Diversität verschiedener Hochschultypen nachzeichnet. Zuletzt untersucht diese Dissertation im Rahmen eines ökonometrischen Input-Output Modells (Stochastic Frontier Analysis), ob die innere Diversität von Hochschulen einen Einfluss auf die finanzwissenschaftliche Effizienz von Hochschulorganisationen nimmt. Die geschätzte Produktionsfunktion weist darauf hin, dass Synergien zwischen bestimmten Fach- und Funktionskombinationen herrschen. Damit kommt diese Arbeit zu dem Schluss, dass breit aufgestellte Universitäten in Deutschland tendenziell effizienter arbeiten

Predicting the Admission into Medical Studies in Germany: A Data Mining approach. Open Access at KIT

In Germany, the placement into medical studies programs is highly competitive. Even for excellent applicants success is uncertain. Tackling this uncertainty, the aim of this paper is to investigate the success of an application. Thus applicant data in the time from 2009 to 2012 was analyzed. The characteristics of the statistical patterns lead us to simple recommendations how to alter an application in order to succeed. Our results indicate that Data Mining can outperform personal predictions

The mass-loss return from evolved stars to the Large Magellanic Cloud III. Dust properties for carbon-rich asymptotic giant branch stars

We present a 2Dust model for the dust shell around a LMC long-period variable (LPV) previously studied as part of the OGLE survey. OGLE LMC LPV 28579 (SAGE J051306.40-690946.3) is a carbon-rich asymptotic giant branch (AGB) star for which we have photometry and spectra from the Spitzer SAGE and SAGE-Spec programs along with UBVIJHK_s photometry. By modeling this source, we obtain a baseline set of dust properties to be used in the construction of a grid of models for carbon stars. We reproduce its spectral energy distribution using a mixture of AmC and SiC (15% by mass). The grain sizes are distributed according to the KMH model. The best-fit model has an optical depth of 0.28 for the shell at the peak of the SiC feature, with R_in~1430 R_sun or 4.4 R_star. The temperature at this inner radius is 1310 K. Assuming an expansion velocity of 10 km s^-1, we obtain a dust mass-loss rate of 2.5x10^-9 M_sun yr-1. We calculate a 15% variation in this rate by testing the fit sensitivity against variation in input parameters. We also present a simple model for the molecular gas in the extended atmosphere that could give rise to the 13.7 \mu m feature seen in the spectrum. We find that a combination of CO and C_2H_2 gas at an excitation temperature of about 1000 K and column densities of 3x10^21 cm^-2 and 10^19 cm^-2 respectively are able to reproduce the observations. Given that the excitation temperature is close to T_dust(R_in), most of the molecular contribution probably arises from the inner shell region. The luminosity corresponding to the first epoch of SAGE observations is 6580 L_sun. For an effective temperature of about 3000 K, this implies a stellar mass of 1.5-2 M_sun and an age of 1-2.5 Gyr. For a gas:dust ratio of 200, we obtain a gas mass-loss rate of 5.0x10^-7 M_sun yr^-1, consistent with the gas mass-loss rates estimated from the period, color and 8 \mu m flux of the source.Comment: 14 pages, 5 figures, accepted for publication in Astronomy & Astrophysic

High angular resolution N-band observation of the silicate carbon star IRAS08002-3803 with the VLTI/MIDI instrument

We present the results of N-band spectro-interferometric observations of the silicate carbon star IRAS08002-3803 with the MID-infrared Interferometric instrument (MIDI) at the Very Large Telescope Interferometer (VLTI) of the European Southern Observatory (ESO). The observations were carried out using two unit telescopes (UT2 and UT3) with projected baseline lengths ranging from 39 to 47 m. Our observations of IRAS08002-3803 have spatially resolved the dusty environment of a silicate carbon star for the first time and revealed an unexpected wavelength dependence of the angular size in the N band: the uniform-disk diameter is found to be constant and ~36 mas (72 Rstar) between 8 and 10 micron, while it steeply increases longward of 10 micron to reach ~53 mas (106 Rstar) at 13 micron. Model calculations with our Monte Carlo radiative transfer code show that neither spherical shell models nor axisymmetric disk models consisting of silicate grains alone can simultaneously explain the observed wavelength dependence of the visibility and the spectral energy distribution (SED). We propose that the circumstellar environment of IRAS08002-3803 may consist of two grain species coexisting in the disk: silicate and a second grain species, for which we consider amorphous carbon, large silicate grains, and metallic iron grains. Comparison of the observed visibilities and SED with our models shows that such disk models can fairly -- though not entirely satisfactorily -- reproduce the observed SED and N-band visibilities. Our MIDI observations and the radiative transfer calculations lend support to the picture where oxygen-rich material around IRAS08002-3803 is stored in a circumbinary disk surrounding the carbon-rich primary star and its putative low-luminosity companion.Comment: 15 pages, 8 figures, accepted for publication in A&

A diagnosis of thickness fluxes in an eddy-resolving model

Output from an eddy-resolving model of the North Atlantic Ocean is used to estimate values for the thickness diffusivity κ appropriate to the Gent and McWilliams parameterization. The effect of different choices of rotational eddy fluxes on the estimated κ is discussed. Using the raw fluxes (no rotational flux removed), large negative values (exceeding −5000 m2 s−1) of κ are diagnosed locally, particularly in the Gulf Stream region and in the equatorial Atlantic. Removing a rotational flux based either on the suggestion of Marshall and Shutts or the more general theory of Medvedev and Greatbatch leads to a reduction of the negative values, but they are still present. The regions where κ < 0 correspond to regions where eddies are acting to increase, rather than decrease (as in baroclinic instability) the mean available potential energy. In the subtropical gyre, κ ranges between 500 and 2000 m2 s−1, rapidly decreasing to zero below the thermocline in all cases. Rotational fluxes and κ are also estimated using an optimization technique. In this case, |κ| can be reduced or increased by construction, but the regions where κ < 0 are still present and the optimized rotational fluxes also remain similar to a priori values given by the theoretical considerations. A previously neglected component (ν) of the bolus velocity is associated with the horizontal flux of buoyancy along, rather than across, the mean buoyancy contours. The ν component of the bolus velocity is interpreted as a streamfunction for eddy-induced advection, rather than diffusion, of mean isopycnal layer thickness, showing up when the lateral eddy fluxes cannot be described by isotropic diffusion only. All estimates show a similar large-scale pattern for ν, implying westward advection of isopycnal thickness over much of the subtropical gyre. Comparing ν with a mean streamfunction shows that it is about 10% of the mean in midlatitudes and even larger than the mean in the Tropics

Failure to Modulate Attentional Control in Advanced Aging Linked to White Matter Pathology

Advanced aging is associated with reduced attentional control and less flexible information processing. Here, the origins of these cognitive effects were explored using a functional magnetic resonance imaging task that systematically varied demands to shift attention and inhibit irrelevant information across task blocks. Prefrontal and parietal regions previously implicated in attentional control were recruited by the task and most so for the most demanding task configurations. A subset of older individuals did not modulate activity in frontal and parietal regions in response to changing task requirements. Older adults who did not dynamically modulate activity underperformed their peers and scored more poorly on neuropsychological measures of executive function and speed of processing. Examining 2 markers of preclinical pathology in older adults revealed that white matter hyperintensities (WMHs), but not high amyloid burden, were associated with failure to modulate activity in response to changing task demands. In contrast, high amyloid burden was associated with alterations in default network activity. These results suggest failure to modulate frontal and parietal activity reflects a disruptive process in advanced aging associated with specific neuropathologic processes

The Mid-IR spatially resolved environment of OH26.5+0.6 at maximum luminosity

We present observations of the famous OH/IR star OH26.5+0.6 obtained using the Mid-Infrared Interferometric Instrument MIDI at the European Southern Observatory (ESO) Very Large Telescope Interferometer VLTI. The emission of the dusty envelope, spectrally dispersed at a resolution of 30 from 8 to 13.5 micron, appears resolved by a single dish UT telescope. In particular the angular diameter increases strongly within the silicate absorption band. Moreover an acquisition image taken at 8.7 micron exhibits, after deconvolution, a strong asymmetry. The axis ratio is 0.75+/-0.07 with the FWHM of the major and minor axis which are 286mas and 214mas respectively. The measured PA angle, 95 degrees +/-6 degrees is reminiscent of the asymmetry in the OH maser emission detected at 1612MHz by Bowers & Johnston (1990) for this star. In interferometric mode the UT1-UT3 102m baseline was employed to detect the presence of the star. No fringes have been found with a detection threshold estimated to be of the order of 1% of the total flux of the source, i.e. 5-8 Jy. These observations were carried out during the phase of maximum luminosity of the star, when the dust shell is more diluted and therefore the chance to detect the central source maximized. We modeled the dusty environment based on the work of Justannont et al. (1996). In particular, the failure to detect fringes provides strong constraints on the opacities in the inner regions of the dust shell or in the close vicinity of the star.Comment: Accepted in A&

Breakdown of Mucin as Barrier to Digestive Enzymes in the Ischemic Rat Small Intestine

Loss of integrity of the epithelial/mucosal barrier in the small intestine has been associated with different pathologies that originate and/or develop in the gastrointestinal tract. We showed recently that mucin, the main protein in the mucus layer, is disrupted during early periods of intestinal ischemia. This event is accompanied by entry of pancreatic digestive enzymes into the intestinal wall. We hypothesize that the mucin-containing mucus layer is the main barrier preventing digestive enzymes from contacting the epithelium. Mucin breakdown may render the epithelium accessible to pancreatic enzymes, causing its disruption and increased permeability. The objective of this study was to investigate the role of mucin as a protection for epithelial integrity and function. A rat model of 30 min splanchnic arterial occlusion (SAO) was used to study the degradation of two mucin isoforms (mucin 2 and 13) and two epithelial membrane proteins (E-cadherin and toll-like receptor 4, TLR4). In addition, the role of digestive enzymes in mucin breakdown was assessed in this model by luminal inhibition with acarbose, tranexamic acid, or nafamostat mesilate. Furthermore, the protective effect of the mucin layer against trypsin-mediated disruption of the intestinal epithelium was studied in vitro. Rats after SAO showed degradation of mucin 2 and fragmentation of mucin 13, which was not prevented by protease inhibition. Mucin breakdown was accompanied by increased intestinal permeability to FITC-dextran as well as degradation of E-cadherin and TLR4. Addition of mucin to intestinal epithelial cells in vitro protected against trypsin-mediated degradation of E-cadherin and TLR4 and reduced permeability of FITC-dextran across the monolayer. These results indicate that mucin plays an important role in the preservation of the mucosal barrier and that ischemia but not digestive enzymes disturbs mucin integrity, while digestive enzymes actively mediate epithelial cell disruption

The modulating effect of education on semantic interference during healthy aging

Aging has traditionally been related to impairments in name retrieval. These impairments have usually been explained by a phonological transmission deficit hypothesis or by an inhibitory deficit hypothesis. This decline can, however, be modulated by the educational level of the sample. This study analyzed the possible role of these approaches in explaining both object and face naming impairments during aging. Older adults with low and high educational level and young adults with high educational level were asked to repeatedly name objects or famous people using the semantic-blocking paradigm. We compared naming when exemplars were presented in a semantically homogeneous or in a semantically heterogeneous context. Results revealed significantly slower rates of both face and object naming in the homogeneous context (i.e., semantic interference), with a stronger effect for face naming. Interestingly, the group of older adults with a lower educational level showed an increased semantic interference effect during face naming. These findings suggest the joint work of the two mechanisms proposed to explain age-related naming difficulties, i.e., the inhibitory deficit and the transmission deficit hypothesis. Therefore, the stronger vulnerability to semantic interference in the lower educated older adult sample would possibly point to a failure in the inhibitory mechanisms in charge of interference resolution, as proposed by the inhibitory deficit hypothesis. In addition, the fact that this interference effect was mainly restricted to face naming and not to object naming would be consistent with the increased age-related difficulties during proper name retrieval, as suggested by the transmission deficit hypothesis.This research was supported by grants PSI2013-46033-P to A.M., PSI2015-65502-C2-1-P to M.T.B., PCIN-2015-165-C02-01 to D.P., PSI2017-89324-C2-1-P to DP from the Spanish Ministry of Economy and Competitiveness (http://www.mineco.gob.es/)