The Research Data Centre of the Centre for European Economic Research (ZEW-FDZ)

Das Zentrum für Europäische Wirtschaftsforschung (ZEW) in Mannheim stellt eine Reihe seiner Forschungsdatensätze externen Wissenschaftlern zur Verfügung. Das ZEW folgt damit den Empfehlungen der „Kommission zur Verbesserung der informationellen Infrastruktur zwischen Wissenschaft und Statistik“ und unterstützt so die Weiterentwicklung der empirischen Wirtschafts- und Sozialforschung. Im November 2012 ist das ZEW-FDZ vom Rat für Sozial und Wirtschaftsdaten (RatSWD) akkreditiert worden. Bei den im ZEW-FDZ angebotenen ZEW Forschungsdaten handelt es sich um Mikrodaten von ZEW Unternehmensbefragungen, ZEW Expertenbefragungen oder ZEW Personenbefragungen. Die Daten einiger ZEW-Befragungen werden externen Wissenschaftlern in einer faktisch anonymisierten Form als Scientific-Use-Files zur Verfügung gestellt. Neben der Nutzung der Scientific-Use-Files können externe Forscher einen Antrag auf Nutzung von formal anonymisierten ZEW-Daten stellen, mit denen sie in den FDZ-Räumen des ZEW arbeiten dürfen. Formal anonymisiert bedeutet, dass die Datensätze weder Namen noch Adressen, aber ansonsten alle Originalangaben der Befragten enthalten. Die formal anonymisierten Daten befinden sich dazu auf einem Stand-alone-Rechner ohne Netzwerkanbindung, von dem keine Daten heruntergeladen werden können. Für das Mannheimer Innovationspanel (MIP) wurden zudem absolut anonymisierte Education-Use-Files für die Nutzung in der Lehre erstellt. Das ZEW-FDZ schließt an die bisherige Praxis des ZEW an, eigene Erhebungsdaten an externe Wissenschaftler weiterzugeben. Vor dem Start des ZEW-FDZ im Januar 2013, stellte das ZEW etwa 280 Wissenschaftlern vom ZEW erhobene Forschungsdaten zur Verfügung; die meisten sind Nutzer des Mannheimer Innovationspanels (250). Das ZEW wird sein Datenangebot für externe Wissenschaftler laufend erweitern. Dies gilt auch für Daten zukünftiger Erhebunge

Supply and Demand for IS Faculty: A Longitudinal Study

The supply and demand of IS professors shifted in the last decade. Understanding the fluctuation of the IS faculty job market is a critical success factor for future planning and recruitment efforts. This paper presents the results of a longitudinal study that monitored the supply and demand of IS professors between 1992 and 2004. Data, primarily from the AIS and ICIS placement services, were analyzed to identify the trends in this market. Other relevant issues such as the composition of IS faculty position applicants, supply of IS doctorates, and trends in IS professor salary are also discussed. The paper concludes with recommendations to business and IS schools based on the findings

Syntaxin 3B is essential for the exocytosis of synaptic vesicles in ribbon synapses of the retina.

Ribbon synapses of the vertebrate retina are specialized synapses that release neurotransmitter by synaptic vesicle exocytosis in a manner that is proportional to the level of depolarization of the cell. This release property is different from conventional neurons, in which the release of neurotransmitter occurs as a short-lived burst triggered by an action potential. Synaptic vesicle exocytosis is a calcium regulated process that is dependent on a set of interacting synaptic proteins that form the so-called SNARE (soluble N-ethylmaleimide sensitive factor attachment protein receptor) complex. Syntaxin 3B has been identified as a specialized SNARE molecule in ribbon synapses of the rodent retina. However, the best physiologically-characterized neuron that forms ribbon-style synapses is the rod-dominant or Mb1 bipolar cell of the goldfish retina. We report here the molecular characterization of syntaxin 3B from the goldfish retina. Using a combination of reverse transcription (RT) polymerase chain reaction (PCR) and immunostaining with a specific antibody, we show that syntaxin 3B is highly enriched in the plasma membrane of bipolar cell synaptic terminals of the goldfish retina. Using membrane capacitance measurements we demonstrate that a peptide derived from goldfish syntaxin 3B inhibits synaptic vesicle exocytosis. These experiments demonstrate that syntaxin 3B is an important factor for synaptic vesicle exocytosis in ribbon synapses of the vertebrate retina

Assessing the operating temperature of multi-junction solar cells with novel rear side layer stack and local electrical contacts

Sub-bandgap sunlight provides a source of heat generation in solar cells that is detrimental to performance, especially in space applications where heat dissipation is limited. In this work we assess the impact that an advanced rear-side contact scheme for multi-junction solar cells has on the cell temperature. Our results show that this scheme reduces the optical power absorption below the bandgap of germanium by 81% compared to a standard, full metallization design. Measurements of the electrical and thermal power fluxes performed in vacuum demonstrate that this lower near-infrared light absorption results in 8% less heat dissipated in the cell with the novel rear-side contact scheme when operating at 25 ºC. Modelling of the operating temperature for both cells when fully encapsulated with glass indicates that this effect will also result in a reduction of the operating temperature of 9 ºC for the novel design

Fabrication tolerant and broadband polarization splitter and rotator based on a taper-etched directional coupler.

We propose a fabrication tolerant polarization splitter and rotator (PSR) on the silicon-on-insulator platform based on the mode-coupling mechanism. The PSR consists of a silicon wire waveguide coupled to a taper-etched waveguide. Compared to previously reported PSRs based on directional couplers which are sensitive to fabrication variations, the partially etched taper structure can compensate for fabrication inaccuracies. In addition, the taper-etched geometry breaks both the horizontal and vertical symmetries of the waveguide, introducing an additional degree of design freedom to accommodate different upper cladding layers. The proposed PSR can be readily integrated in a planar waveguide circuit using e.g. SiO(2) cladding, making it compatible with typical metal back-end-of-line processes. Our simulation results show that the PSR has a low TM-to-TE polarization conversion loss of -0.09 dB in the C-band (or a conversion efficiency of 98%). A low TE-to-TE through insertion loss (-0.07 dB) and a very low polarization crosstalk (-30 dB) over a wide wavelength range exceeding 160 nm with a large fabrication tolerance (50 nm) are numerically demonstrated

The sensitivity of harassment to orbit: Mass loss from early-type dwarfs in galaxy clusters

We conduct a comprehensive numerical study of the orbital dependence of harassment on early-type dwarfs consisting of 168 different orbits within a realistic, Virgo-like cluster, varying in eccentricity and pericentre distance. We find harassment is only effective at stripping stars or truncating their stellar discs for orbits that enter deep into the cluster core. Comparing to the orbital distribution in cosmological simulations, we find that the majority of the orbits (more than three quarters) result in no stellar mass loss. We also study the effects on the radial profiles of the globular cluster systems of early-type dwarfs. We find these are significantly altered only if harassment is very strong. This suggests that perhaps most early-type dwarfs in clusters such as Virgo have not suffered any tidal stripping of stars or globular clusters due to harassment, as these components are safely embedded deep within their dark matter halo. We demonstrate that this result is actually consistent with an earlier study of harassment of dwarf galaxies, despite the apparent contradiction. Those few dwarf models that do suffer stellar stripping are found out to the virial radius of the cluster at redshift = 0, which mixes them in with less strongly harassed galaxies. However when placed on phase-space diagrams, strongly harassed galaxies are found offset to lower velocities compared to weakly harassed galaxies. This remains true in a cosmological simulation, even when haloes have a wide range of masses and concentrations. Thus phase-space diagrams may be a useful tool for determining the relative likelihood that galaxies have been strongly or weakly harassed