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Die Statistik als fachliche Disziplin muss sich in einem rasch wandelnden Umfeld behaupten, das durch den Aufstieg der Data Science, den Bedeutungszuwachs der künstlichen Intelligenz sowie neue Datenstrukturen charakterisiert wird. Wie kann sich die Statistik hier behaupten oder verlorenes Terrain wiedergewinnen? Unter dem provokanten Motto „Make Statistics great again“ wurden aus verschiedenen Blickwinkeln Entwicklungen, Strategien und positive Beispiele skizziert, wie sich das Fach Statistik an der Universität, im Wissenschaftsbetrieb und auf dem Arbeitsmarkt positionieren sollte. Willi Seidel schaut aus dem Blickwinkel eines Hochschulpräsidenten auf den Ressourcenkampf der Fächer. Christine Müller berichtet über die Initiativen der Dachorganisation DAGStat die vielen Teildisziplinen der Statistik wirkungsvoll im Wissenschaftsbetrieb und in der Öffentlichkeit zu positionieren. Florian Meinfelder dokumentiert den Aufstieg des Masterstudiengangs in Survey Statistik zu einem der nachgefragtesten Studiengänge der Uni Bamberg. Jürgen Chlumsky und Markus Zwick beleuchten die historische Wahrnehmung der Amtsstatistik bei Pflichterhebungen und die Entwicklung der Forschungsdatenzentren sowie moderner Zugänge zu neuen Datenquellen. Joachim Wagner schildert das Verhältnis von Datenproduzenten und Datennutzern aus der Sicht eines unzufriedenen Datennutzers. Schließlich geht es um die Position der Statistik in der Datenwissenschaft. Ist „Data Science“ nur ein neumodisches Wort für Statistik? Ein Konzeptionspapier der Gesellschaft für Informatik (GI) hat zu Positionspapieren der DStatG und der DAGStat geführt, die von Ulrich Rendtel vorgestellt werden. Das Kolloquium fand anlässlich der Abschiedsvorlesung von Ulrich Rendtel im Juni 2019 am Fachbereich Wirtschaftswissenschaft der Freien Universität statt., Statistics as a subject has to sustain its position in a fast changing environment which is characterized by the rise of Data Science, the growth of the importance of Artificial Intelligence and the emergence of new Data Structures. How can Statistics keep its position or even regain lost territory? Under the provoking motto “Make Statistics great again” we sketch under different views developments, strategies and positive examples, how the subject statistics can evolve at universities, in scientific competition and at the labor market. Willi Seidel comments the competition of subjects for resources from the viewpoint of the head of a university. Christine Müller reports the initiatives of the DAGStat umbrella organization, to promote the different subbranches of statistics in the scientific competition and in the public view. Florian Meinfelder documents the rise of the master program of Survey Statistics to one of the most requested master programs at the university of Bamberg. Jürgen Chlumsky and Markus Zwick report the public notion of mandatory surveys of official statistics as well as the development of research data centers and alternative access to new data sources. Joachim Wagner comments the relationship of data producers and data users from the view of a discontent data analyst. Finally, the position of statistics in the subject data science is discussed. Is the term “Data Science” only a modern phrase for statistics? A White Paper of the Gesellschaft für Informatik (GI) has provoked two position papers of the DStatG and the DAGStat which are presented by Ulrich Rendtel. The colloquium took place at the farewell lecture of Ulrich Rendtel at the Economic Faculty of the Freie Universität Berlin in June 2019.

This article presents a review of the evolution of automatic post-editing, a term that describes methods to improve the output of machine translation systems, based on knowledge extracted from datasets that include post-edited content. The article describes the specificity of automatic post-editing in comparison with other tasks in machine translation, and it discusses how it may function as a complement to them. Particular detail is given in the article to the five-year period that covers the shared tasks presented in WMT conferences (2015–2019). In this period, discussion of automatic post-editing evolved from the definition of its main parameters to an announced demise, associated with the difficulties in improving output obtained by neural methods, which was then followed by renewed interest. The article debates the role and relevance of automatic post-editing, both as an academic endeavour and as a useful application in commercial workflows.

The ‘optical fold’ of Evermanella balbo covers the ventro-lateral cornea and is presumed to capture illumination that would otherwise remain undetected by the tubular eye of this mesopelagic teleost. It contains alternating bands of cellular and acellular material, running approximately perpendicular to the lateral surface of the eye. Only parts of this lamellar body lie within the eyelid-like structure. The cellular lamellae are 2–2.5 μm thick centrally and composed of fibroblast-like cells. The extracellular bands (4.5–5 μm thick) contain regular arrays of collagen fibrils, with layers of thin fibrils sandwiching a region of thicker fibrils. The thin fibrils are organised in alternating sheets where fibrils, although all parallel, change their orientation by 90° between each sheet. All thick fibrils are oriented parallel to the lateral surface of the ‘optical fold’. In the main retina, small bundles of rod inner/outer segments are separated by the processes of the retinal pigment epithelium (rpe) laterally. Centrally, the length of tightly packed rods increases, but rpe processes no longer divide them into bundles. Medially, rod length increases further, but packing is less dense. The accessory retina is significantly thinner, and less well-developed than the main retina. Ventrally, the rods show no regular arrangement and are not grouped. Dorsally, however, rods are arranged into bundles, separated by melanosome-filled rpe processes. The thickness of the retina increases as it approaches the crystalline lens. It is on this dorsal accessory retina that light traversing the ‘optical fold’ most likely falls, facilitating the detection of moving objects in the ventro-lateral field of view.

This study uses strictly comparable data for small and medium sized enterprises from industry or services in 25 European countries to test for links between credit restrictions and export activities of firms (participation in exports and share of exports in total sales). Data were collected in the Survey on Access to Finance of Enterprises (SAFE) conducted on behalf of the European Commission and the European Central Bank. Credit restrictions are measured by the importance of problems related to access to finance reported by the firms. Contrary to the big picture revealed by a comprehensive literature survey a statistically significant negative relationship between more severe problems in access to finance and exports is only rarely found.

Highly charged polymer colloids may serve as model systems for the investigation of condensed matter, if they self-organize to liquid-like, glassy or crystalline phases. Multiple scattering due to refractive index differences of colloidal particles and suspending medium is a serious problem when utilizing light scattering experiments for these investigations. In this work, a new class of monodisperse colloidal dispersions is prepared by means of emulsion copolymerization of the monomers n-butyl acrylate and 2,2,2-trifluoroethyl acrylate. By systematic variation of the molar ratio of fluorinated and non-fluorinated monomers, the refractive index n p of the colloidal copolymer particles is tuned in the range 1.38 < n p < 1.45. Thus, particles with any composition of both monomers can be index-matched by protic water/glycerol mixtures as demonstrated by minima of the relative transmission of suspensions in dependence on the refractive index of the suspending medium. Static and dynamic light scattering experiments as well as analysis of the static structure factors S(Q) by means of integral equations are employed to investigate the self-organization of the resulting colloidal copolymer particles. Hereby, the potential application of these new model systems to investigate dynamics in concentrated binary mixtures is demonstrated.

Defect repair of GaN-based light-emitting diodes (LEDs) by ultraviolet laser micromachining is reported. Percussion and helical drilling in GaN by laser ablation were investigated using 248 nm nanosecond and 355 nm picosecond pulses. The influence of laser ablation including different laser parameters on electrical and optical properties of GaN-based LED chips was evaluated. The results for LEDs on sapphire with transparent conductive oxide p-type contact on top as well as for thin-film LEDs are reported. A reduction of leakage current by up to six orders in magnitude and homogeneous luminance distribution after proper laser defect treatment were achieved.

A vast literature on the international activities of heterogeneous firms finds the existence of a positive exporter productivity premium. On average, exporting firms are more productive than firms that sell on the national market only. The Melitz (Econometrica 71:1695-1725, 2003) model, however, has implications for not only mean differences but also differences in the distribution of productivity. Furthermore, exporting firms may be different from non-exporting firms for reasons that are not included in the Melitz model. We believe that conditioning on firm fixed effects and studying the distribution of productivity are both necessary for empirical tests of the Melitz model. This paper is the first to employ a new quantile estimation technique for panel data introduced in Powell (Did the economic stimulus payments of 2008 reduce labor supply? Evidence from quantile panel data estimation. RAND Corporation Publications Department, Santa Monica, 2014). We find that the premium is positive at all productivity levels, but highest at the lowest quantiles. These results support theoretical models which suggest that there is a division in productivity between exporters and non-exporters.

Eutectic aluminum–germanium wafer bonding was used to fabricate (AlGaIn)N thin-film light-emitting diodes (LEDs). Wafer bonding was carried out on 2″ wafer level at a bond temperature of 470 °C using patterned Al bond pads on the GaN-on-sapphire LED epiwafer and plain Ge substrates. The microstructure of the joint formation was characterized via cross-section analysis using scanning electron microscopy and energy dispersive X-ray spectroscopy (EDX). Scanning acoustic microscopy was used to investigate the bond interface. The shear strength was determined to be 1–2 kN/cm2. The formation of a liquid Al–Ge phase is evident from cross-section analysis and optical microscopy. During solidification, Al and Ge are separated into distinct phases again, which is revealed by EDX. The obtained bond is not free of micro-voids, yet it is mechanically stable and suited for the fabrication of thin-film LEDs by removing the sapphire substrate via laser lift-off, which is also demonstrated.

The literature on international trade and firm performance grows exponentially. This paper attempts to summarize what we learn from this literature to guide both future empirical and theoretical work in this area, and public debates and policy makers, in an evidence-based way. The focus is on the empirical part of the literature that consists of recently published papers using data for firms from manufacturing or services industries to study the links between international trade (exports and imports) and dimensions of firm performance (productivity, wages, profitability and survival). It discusses recent add-ons to the box of tools for empirical investigation in this field and suggests topics for future research.

This paper compares the performance of alternative cost-based transfer pricing methods. We adopt an incomplete contracting framework with asymmetric information at the trading stage. Transfer pricing guides intra-company trade and provides incentives for value-enhancing specific investments. We compare actual-cost transfer prices that include a markup over marginal costs with standard-cost transfer prices that are determined either by the central office ex ante (centralized standard-cost transfer pricing) or by the supplying division at the trading stage (reported standard-cost transfer pricing). For the actual-cost methods, we show that markups based on the joint contribution margin (contribution-margin transfer pricing) dominate purely additive markups (cost-plus transfer pricing). We obtain the following results. (1) Centralized standard-cost transfer pricing dominates the other methods if the central office and the divisions ex ante face low cost uncertainty. (2) The actual-cost methods dominate the other methods if the central office and the divisions ex ante face high cost uncertainty and later, at the trading stage, the buying division receives sufficient cost information. (3) Reported standard-cost transfer pricing dominates the other methods if the central office and the divisions ex ante face high cost uncertainty, and the buyer has insufficient cost information at the trading stage.

Im deutschen Arbeits- und Sozialrecht gibt es rund 160 Schwellenwerte. Diese geben an, ab welcher Beschaftigtenzahl ein bestimmtes Gesetz oder eine Regelung in einem Betrieb zur Anwendung kommt (z. B. Kundigungsschutzgesetz). Da das Uberschreiten von Schwellenwerten meist mit zusatzlichen Kosten fur die Betriebe verbunden ist (z. B. Gewahrung von (Mitbestimmungs-)Rechten oder Einhaltung von Schutzstandards), wird vermutet, dass diese das Beschaftigungswachstum in Betrieben mit einer Beschaftigtenzahl unterhalb einer Schwelle bremsen. Umgekehrt wird Schwellenwerten unterstellt, dass sie den Beschaftigungsabbau in Betrieben oberhalb einer Schwelle fordern. Im Rahmen des DFG-Projekts wurde diesen Vermutungen nachgegangen. Dazu wurde auf Basis verschiedener Datensatze okonometrisch uberpruft, ob von der Beschaftigungspflicht fur Schwerbehinderte, der Freistellung des ersten Betriebsrats von seiner beruflichen Tatigkeit oder einer der 13 Regelungen rund um den 20er-Schwellenwert ein Einfluss auf die Beschaftigungsdynamik in Betrieben rund um die jeweilige Schwelle ausgeht, wobei sich nur selten die erwarteten Bremseffekte zeigten. Da Schwellenwertregelungen sehr unterschiedlich ausgestaltet sind, wurde zudem ein Vorschlag fur deren Vereinheitlichung erarbeitet, um Transaktions- und Informationskosten zu senken und Ausweichreaktionen zu vermeiden.

We present the time-resolved spectral analysis of the settling process in a pulsed external-cavity quantum-cascade laser (EC-QC laser) emitting in the wavelength range around 7.4 μm. Due to mode competition between the two cavities formed by the laser-chip on one hand and the external-cavity on the other hand, a time-dependent spectral emission on a ns time-scale can be observed. Depending on the spectral characteristic of the external cavity with respect to the chip gain curve time-delays of the external cavity emission of 15–35 ns within the 100 ns drive pulse can be observed.

Zahlreiche Untersuchungen belegen, dass die exportierenden Firmen den nur für den Inlandsmarkt produzierenden Firmen in vieler Hinsicht überlegen sind – sie sind im Durchschnitt größer, produktiver und innovativer, und sie waren dies schon, bevor sie mit dem Export begonnen haben. Eine offene Frage ist, wie und in welchem Maße die Firmen dann vom Export profitieren. Ökonometrische Auswertungen auch der Basis von Längsschnittdaten von Firmen zeigen nur selten positive Auswirkungen der Exportaktivitäten. Dies kann auch an den hierbei verwendeten Methoden liegen, denn ein Vergleich der exportierenden Firmen mit sich selbst in einer Situation ohne Export ist ja nicht möglich. Eine direkte Befragung von Exporteuren kann hier neue Erkenntnisse bringen. Eine Befragung von exportierenden Firmen aus den IHK-Bezirken Lüneburg- Wolfsburg und Stade zeigt, dass die Firmen sehr heterogen sind – nicht alle profitieren in gleicher Weise und in gleichem Maße vom Export. Große positive Effekte finden sich bei mehr als der Hälfte der Firmen bezogen auf Wachstum, Kapazitätsauslastung und Erträge sowie bei rund 40 Prozent mit Bezug auf den Ausgleich inländischer Konjunkturschwankungen. Umgekehrt sieht es bei den „Lerneffekten“ (Anregungen von Auslandskunden zur Verbesserung der Produkte; Steigerung der Produktivität als Reaktion auf höheren Wettbewerbsdruck auf Auslandsmärkten; bessere Einschätzung der eigenen Konkurrenzfähigkeit aufgrund von Kontakten mit Konkurrenten auf Auslandsmärkten und daraus folgende entsprechende Reaktionen) aus – hier überwiegen deutlich die Angaben wonach keine oder allenfalls geringe Effekte vorliegen. Was erklärt die in der Befragung festgestellten Unterschiede zwischen den Firmen in Bezug auf die Auswirkungen der Exporttätigkeit? Als zentrales Ergebnis können wir festhalten, dass bis auf den Exportanteil am Umsatz keine der anderen betrachteten Firmeneigenschaften wie Größe, Dauer der Exporterfahrung, Forschungs- und Entwicklungstätigkeit oder Auslandsniederlassungen ausschlaggebend dafür sind, ob eine Firma vom Export in verschiedener Hinsicht positiv beeinflusst wird oder nicht. Vom Export können also sehr unterschiedliche Firmen gleichermaßen profitieren, wobei tendenziell die Wahrscheinlichkeit dafür, dass ein starker positiver Effekt zu beobachten ist, mit zunehmendem Anteil des Auslandsumsatzes am Umsatz ansteigt. Simulationsrechnungen mit den geschätzten Modellen zeigen hierbei: Wenn es Effekte des Exports gibt, dann werden diese in der Regel erst ab einem Exportanteil am Umsatz von mindestens 25 Prozent deutlich.

Germany is one of the most important exporters of manufacturing goods in the world, but by far not all manufacturing firms in Germany are exporters, and there is a remarkable gap between the share of exporters in all manufacturing firms between West Germany and East Germany. While in West Germany in 2004 about two in three manufacturing plants were exporters, fourteen years after re-unification this share was less than fifty percent in the former communist East Germany. Given that exports play a key role in shaping business cycles and growth in Germany, and the much higher unemployment in East compared to West Germany, promotion of exports by East German firms figure prominently on the policy agenda ... Germany is one of the most important exporters of manufacturing goods in the world, but by far not all manufacturing firms in Germany are exporters, and there is a remarkable gap between the share of exporters in all manufacturing firms between West Germany and East Germany. While in West Germany in 2004 about two in three manufacturing plants were exporters, fourteen years after re-unification this share was less than fifty percent in the former communist East Germany. Given that exports play a key role in shaping business cycles and growth in Germany, and the much higher unemployment in East compared to West Germany, promotion of exports by East German firms figure prominently on the policy agenda ...

Human primordial germ cells and mouse neonatal and adult germline stem cells are pluripotent and show similar properties to embryonic stem cells. Here we report the successful establishment of human adult germline stem cells derived from spermatogonial cells of adult human testis. Cellular and molecular characterization of these cells revealed many similarities to human embryonic stem cells, and the germline stem cells produced teratomas after transplantation into immunodeficient mice. The human adult germline stem cells differentiated into various types of somatic cells of all three germ layers when grown under conditions used to induce the differentiation of human embryonic stem cells. We conclude that the generation of human adult germline stem cells from testicular biopsies may provide simple and non-controversial access to individual cell-based therapy without the ethical and immunological problems associated with human embryonic stem cells.

In public discussion in Germany it is often argued that jobs are mainly created in small and medium-sized firms (i.e. the "Mittelstand"), whereas large firms tend to reduce their number of jobs. An empirical analysis for the period 1999 to 2005 with data of all western and eastern German firms that have at least one employee covered by social insurance shows that the "job engine Mittelstand" hypothesis is too undifferenciated. While small and medium-sized firms contribute more than proportionally to job growth, they are also heavily involved in job losses. In contrast, large firms with 250 employees and more record shares of job growth and destruction which are lower than their share in employment. This implies that economic policy measures which focus on certain size classes of firms cannot be justified by superior employment growth in these size classes.

Wafers cut from Si-doped vertical gradient freeze (VGF) GaAs crystals with silicon concentration varying from 1.5 to 3.4 × 1018 cm−3 have been investigated by low temperature photoluminescence topography. Carrier concentration maps were calculated from intensity topograms recorded on the high-energy slope of the band-to-band recombination, which depends on the carrier concentration predominantly due to band renormalization and band filling. Comparison to maps recorded on the BAs-related PL band reveal a clear anti-correlation consistent with the view of BAs complex formation.

The Mg doping profiles in close proximity to the (AlGaIn)N/GaN QW active region of group III-nitride light-emitting diodes grown by low pressure metal-organic vapor-phase epitaxy on sapphire substrates were investigated by secondary ion mass spectrometry (SIMS) depth profiling. The actual Mg profiles close to the active region have been found to be influenced by segregation as well as by back-diffusion during growth and can be controlled by appropriate growth temperatures. From the Mg depth profiles we estimated an activation energy of 4.5−4.7 eV for Mg diffusion in (AlGa)N.

In der vorliegenden Arbeit wurde das Dilemma der pretialen Lenkung in einer Welt unvollstandiger Vertrage einer erneuten Untersuchung unterzogen. Als Ergebnis zeigte sich, dass eine zentrale Planung gegenuber einer dezentralen Steuerung mit Verrechnungspreisen uberlegen ist, wenn eine hinreichend positive Korrelation zwischen Kosten- und Erlosentwicklung besteht (und vice versa). Darauf aufbauend wurde untersucht, inwieweit Effizienzsteigerungen mit einem hybriden Mechanismus im Sinne von Edlin/Reichelstein (1995) moglich sind, wobei erweiternd davon ausgegangen wurde, dass von den Parteien das ursprunglich geplante Bereichsergebnis im Rahmen ihrer Verhandlungen unterschiedlich stark geltend gemacht werden kann.

Mit einem Paneldatensatz für sämtliche niedersächsischen Industriebetriebe der Jahre 1995 bis 2002 werden drei Hypothesen aus dem Modell von Hopenhayn (Econometrica 1992) getestet: (H1) Firmen, die in der Periode t aus dem Markt ausscheiden, waren in der Periode t-1 weniger produktiv als Firmen, die in t im Markt verbleiben. (H2) Firmen, die in der Periode t in den Markt eintreten, weisen eine geringere Produktivität auf als Firmen, die in der Periode t bereits im Markt aktiv sind. (H3) Firmen aus einer Gründungskohorte, die am Markt überleben, weisen zum Zeitpunkt der Gründung eine höhere Produktivität auf als Firmen, die bereits nach wenigen Jahren wieder ausscheiden. Jede Hypothese wird bestätigt. Ergebnisse aus Analysen mit anderen Daten stützen diese Befunde. Dies zeigt, dass Selektionseffekte, bei denen die produktivsten Betriebe überleben, die Dynamik von Industrien prägen. Wirtschaftspolitische Maßnahmen, die Markteintritte und Marktaustritte oder Reallokationsprozesse von Produktionsfaktoren zwischen bereits bestehenden Betrieben behindern, bremsen damit das Wachstum der Produktivität und so das Wirtschaftswachstum insgesamt. Sie sollten daher unterbleiben.

To show the effects of different concentrations of contrast agent on signal time curves and image contrast of abdominal aorta, vena cava and portal vein in comparison to each other as well as liver and spleen. Imaging was carried out in a 1.0 Tesla clinical scanner. Sixty patients were prospectively included and divided into three contrast agent (Gd-DTPA) dosage groups (0.1 mmol/kg, 0.2 mmol/kg and 0.3 mmol/kg). All patients were scanned using a time-resolved 3D FLASH sequence (58 phases) with a 3.75 second acquisition time per phase. Signal time curves and image contrast levels were evaluated. No significant differences were found for the maximum signal enhancement between the groups in the investigated vessels. Image masking, the subtraction of the baseline images, resulted in a substantial improvement in image contrast. However, statistically significant differences between the contrast agent dosage groups could only be found for vena cava and liver. Vessel conspicuity is not significantly improved with an increase of contrast agent dose. However, an increase in contrast agent dosage increases vessel contrast. Our findings suggest that a single dose single station investigation seems to be sufficient for high quality abdominal MRA.

To evaluate the efficacy of NF-kappa B oligonucleotides (ODN) administered by local administration with the channeled balloon catheter to prevent restenosis after balloon angioplasty in restenotic iliac arteries of New Zealand white rabbits.In vitro, 8000 rabbit vascular smooth muscle cells (rVSMC) where transfected with a liposomal carrier (TfX50) with 100 ng of decoy and scrambled ODN. Inhibition of proliferation was measured using a MTT assay after 24 hours in comparison to control. In vivo, 22 male New Zealand White rabbits were fed a 1% cholesterol diet and received denudation of both common iliac arteries with a 3 mm balloon catheter to induce an arterial stenosis. Four weeks after stenosis induction, local application of NF-kappa B in two different concentrations (1 mug: n = 14; 10 mug: n = 8) was performed randomly on one common iliac artery. Scrambled oligonucleotides without specific binding capacities were injected into the contralateral side. The channeled balloon catheter allows simultaneous balloon dilation (8 atm) of the stenosis and local application of a drug solution (2 atm). Four weeks after local drug delivery the animals were killed and the vessels were excised and computerized morphometric measurements were performed.NF-kappa B decoy ODN but not scrambled ODN inhibited proliferation of rVSMC in vitro. Following local ODN application in the animals, no acute vascular complications were seen. NF-kappa B ODN resulted in a statistically non significant reduction of neointimal area compared to the control group. The neointimal area was 0.97 mm(2) using 1 mug NF-kappa B ODN compared to 0.98 mm(2) in the control group. The higher dose resulted in a neointimal area of 0.97 mm(2) compared to 1.07 mm(2) at the control side.Local drug delivery of NF-kappa B ODN using the "channeled balloon" catheter could not reduce neointimal hyperplasia in stenostic rabbit iliac arteries. Application modalities have to be improved to enhance the effect of the local application to prevent restenosis after balloon angioplasty.

Hepatische Metastasen neuroendokriner Tumoren stellen einen negativen prognostischen Faktor sowohl fur die Uberlebenszeit als auch die Lebensqualitat der Patienten dar. Die Rationale der lokalen Behandlung der hepatischen Filiae ergibt sich aus der haufig auf die Leber beschrankten Metastasierung oder durch medikamentos nicht beherrschbare Symptome der neuroendokrinen Lebermetastasen. Als Alternative zur chirurgischen Resektion der Metastasen wurden eine Reihe von lokalen Therapieverfahren entwickelt. Zu den etablierten Verfahren zahlen die Embolisation und Chemoembolisation, die sich wegen der Hypervaskularisation und hepatisch-arteriellen Gefasversorgung anbieten, und die perkutane Alkoholinjektion. Neuere Verfahren sind die Radiofrequenztherapie, die laserinduzierte interstitielle Tumortherapie und die Kryotherapie. Nachfolgend werden die einzelnen Verfahren, ihre Indikationen, Ergebnisse und Komplikationen hinsichtlich der Behandlung von Lebermetastasen neuroendokriner Tumoren vorgestellt.

This paper uses an unbalanced panel data set for exporting firms from manufacturing industries in one German Federal state, Lower Saxony, to investigate the microstructure of the recent export boom. Looking at data for 1995/96 - 2001/2002 it is demonstrated that a considerable number of plants start and stop exporting in each year, but that most of the export dynamics is due to positive and negative changes of exports in plants that continue exporting. A small fraction made of 4 - 5 percent of all exporting plants is responsible for around 70 to 80 percent of the gross increase in exports... This paper uses an unbalanced panel data set for exporting firms from manufacturing industries in one German Federal state, Lower Saxony, to investigate the microstructure of the recent export boom. Looking at data for 1995/96 - 2001/2002 it is demonstrated that a considerable number of plants start and stop exporting in each year, but that most of the export dynamics is due to positive and negative changes of exports in plants that continue exporting. A small fraction made of 4 - 5 percent of all exporting plants is responsible for around 70 to 80 percent of the gross increase in exports. Firms with expanding and contractingexports are found simultaneously in all broad sectors, technology classes and firmsize classes. Patterns of export behavior differ widely between the plants over theperiods investigated.

This paper contributes to empirical research on the role of regional policy for entrepreneurship by focusing on the link between two stylized facts that emerged from a number of studies for Germany and other countries: Entry rates differ between regions, and the propensity to become an entrepreneur is influenced by socio-demographic variables and attitudes. We develop a theoretical framework to discuss this link, and we test whether for a person of a given age, degree of schooling, attitude towards risk etc. regional variables and, therefore, regional policies, do matter for the decision to start a new business ceteris paribus. Our econometric study is based on data for 10.000 persons from a recent representative survey of the population in ten German planning regions, the Regional Entrepreneurship Monitor (REM). We use a version of the probit model that takes care of the regional stratification of the data, and the results of the nonlinear models are carefully interpreted and illustrated. We find that the propensity to step into self-employment is, among others, higher for males, unemployed, people with contacts to a role model, and with past entrepreneurial experience, who live in more densely populated and faster growing regions with higher rates of new firm formation, while risk aversion and high prices of land have the opposite impact. Interestingly, it does not matter whether the region has a "left" or "right" government. However, many implications for entrepreneurship supporting policies in German regions are discussed in the final section.

Mit der klinischen Anwendung neuer Rekanalisationstechniken wie der Verwendung hydrophil beschichteter Fuhrungsdrahte und der Implantation von Stents bzw. Stentgrafts hat die technische Erfolgsrate endovaskularer Interventionen zur Perfusionsverbesserung bei peripherer arterieller Verschlusskrankheit (pAVK) im letzten Jahrzehnt eine wesentliche Verbesserung erfahren. Gelingt es, die—auch langstreckige—Obstruktion initial zu rekanalisieren, so kann mit den modernen Techniken der Interventionsradiologie das arterielle Gefas in der Regel suffizient eroffnet werden. Die hervorragenden Akutergebnisse werden limitiert durch die im Langzeitverlauf in Abhangigkeit von der Gefasregion in unterschiedlichem Ausmas auftretende Rezidivstenose. Wahrend im aortoiliakalen Gefassegment aufgrund der Grose der therapierten Gefase und des exzellenten Flusses Rezidivstenosen kaum klinische Bedeutung haben, treten diese im femoropoplitealen Gefassegment und insbesondere an den kruralen Arterien haufiger auf. Dies fuhrt zu einer Differentialindikation der endovaskularen Therapie, wobei wir in einem interdisziplinaren Konsen- sus zunehmend die endovaskulare Therapie aortoiliakaler Obstruktionen als primare Behandlungsmasnahme allen Patienten anbieten, im Bereich der Femoralisgabel eine klare primare Indikation zur offen-chirurgischen Behandlung sehen und uns im femoropoplitealen Segment unter Abwagung von Verschlusslange, Risikofaktoren des Patienten und Komorbiditaten bei kurzen Obstruktionen (< 10 cm) eher fur ein primar endovaskulares Verfahren und bei langeren Obstruktionen fur ein primar gefaschirurgisches Verfahren entscheiden. Bei infrapoplitealen Lasionen sehen wir die initiale Option der endovaskularen Therapie aufgrund der reduzierten Invasivitat der vorwiegend alteren und multimorbiden Patientenkohorte. Die weitere klinische Forschung zur Evaluation endovaskularer Therapieverfahren bei pAVK der unteren Extremitaten erfordert dringend Outcomestudien, die sorgfaltig klinisch relevante Endpunkte einschliesen, um den Stellenwert der endovaskularen Therapiemasnahmen gegenuber den traditionellen gefaschirurgischen Bypassverfahren klar darzulegen. Bis diese vorliegen, scheint das transatlantische Konsensuspapier verschiedener gefastherapeutisch orientierter Fachgesellschaften (TASC) als Leitlinie sinnvoll.

Adoptive immunotherapy with Epstein-Barr virus (EBV)-specific cytotoxic T cells (CTL) is effective for the prophylaxis and treatment of EBV-induced lymphoma in hematopoietic stem cell recipients. However, in EBV-positive Hodgkin's disease (HD) the efficacy of adoptively transferred EBV-specific CTL may be limited by tumor-derived immunosuppressive factors, such as T-cell growth factor (TGF) beta, interleukin (IL)13 and the chemokine TARC. Local delivery of IL12 to tumor sites by tumor-specific CTL could provide direct antitumor effects and overcome the CTL-inhibitory effects of the Th2 tumor environment while avoiding the systemic toxicity of recombinant IL12. EBV-specific CTL transduced with a retrovirus vector expressing the p40 and p35 subunits of IL12 as a single molecule (Flexi-IL12), produced IL12 following antigenic stimulation. This resulted in an elevated production of Th1 cytokines, including interferon gamma and tumor necrosis factor alpha, and a reduction in the Th2 cytokines IL4 and IL5. Flexi-IL12-transduced CTL resisted the antiproliferative and anticytotoxic effects of exogenous TGFbeta, likely by antagonizing the TGFbeta-induced downregulation of the Th1 transcriptional factor T-bet. In addition, Flexi-IL12-transduced CTL demonstrated a proliferative advantage in the presence of inhibitory supernatants from HD-derived cell lines. Tumor-specific, Flexi-IL12-transduced EBV-specific CTL should have a functional advantage over unmodified CTL, particularly in the presence of the adverse Th2 cytokine environment produced by Hodgkin tumor cells.

Priapism can be divided into "low-flow" veno-occlusive priapism and, especially in children, rare "high-flow" arterial priapism. We report a 5-year-old boy who developed arterial priapism after blunt perineal trauma that was successfully treated by superselective embolization with microcoils.

Using a large new data set we present results from the first econometric study of the effects of pensions on firm performance in Germany. We find evidence for positive effects on wages, reduction of labor trunover, training, and profits. Using a large new data set we present results from the first econometric study of the effects of pensions on firm performance in Germany. We find evidence for positive effects on wages, reduction of labor trunover, training, and profits.

The positive relationship between firm size and direct exports is often considered as a stylized fact. Numerous econometric investigations back theoretical considerations by showing that a ceteris paribus positive relationship between firm size and direct export activities exists. This note contributes to the literature by closely looking at an econometric modelling issues that has largely been neglected hitherto. Various approaches used in the literature to model the exports/sales ratio, which is a percentage variable with usually many observations at the lower limit, are discussed. It is argued that all these methods are seriously flawed, and an alternative approach is suggested that is applied using data from a large comprehensive recent survey of German manufacturing establishments. Furthermore, the relation between firm size and exports is examined in four selected industries to test whether the importance of economies of scale and transaction cost efficiencies vary considerably between industries.

Evaluation of C-arm-supported CT fluoroscopy to facilitate percutaneous abscess drainage procedures.Prospectively, 40 percutaneous drainage procedures were performed either with C-arm-supported CT fluoroscopy or with CT fluoroscopy alone. Hybrid imaging was performed on the CT couch after complementing a CT fluoroscopy scanner with a C-arm fluoroscopy unit. Procedure times, drainage revisions during follow-up, and postinterventional drainage periods were analyzed.When compared with exclusive CT fluoroscopic guidance, a median procedure time of 9 +/- 3.7 min versus 14.8 +/- 7.3 min was required for C-arm-supported CT fluoroscopy (p0.005, t-test). During follow-up, eight drainage catheters had to be revised within the exclusive CT fluoroscopy group, while only two revisions were necessary within the C-arm-supported CT fluoroscopy group. With C-arm-supported CT fluoroscopy, postinterventional drainage periods were reduced (median 13 vs 19 days; p0.001, t-test).Compared with exclusive cross-sectional image guidance, C-arm-supported CT fluoroscopy seems to improve placement of abscess drainage catheters to possibly reduce procedure times, drainage catheter revisions, and postinterventional drainage periods.

To determine whether covered self-expanding metal stents successfully exclude experimentally created esophagotracheal fistulas.Esophagotracheal fistulas were surgically created in the upper third of the esophagus in 12 minipigs and immediately sealed by implantation of a covered self-expanding metal stent (20 mm expanded diameter) in the esophagus. Before the animals were killed, after 3, 7, 14, 28, 30, and 36 days, the position of the stent and the sealing of the fistula were monitored fluoroscopically. The esophagus, trachea, and both lungs were examined histologically.Creation of an esophagotracheal fistula was successful in all cases. All fistulas were widely patent at autopsy. The technical success rate for stent deployment and initial sealing of the fistula was 100%. During follow-up, five stents migrated distally, but none into the stomach. Therefore, the fistula was no longer excluded in five animals. In seven animals the stent sealed the fistula until the death of the animal. Tracheal narrowing necessitated additional tracheal stenting in three animals. Two minipigs died due to aspiration of food. Histologic examination showed signs of aspiration in all animals with stents in place for longer than 2 weeks.This experimental animal study revealed worse results for sealing of esophagotracheal fistulas with covered self-expanding metal stents than have been reported for the clinical use of these devices.

Spectroscopic ellipsometry (SE) has been used for the characterization of AlGaN/GaN and InGaN/GaN heterostructures. The resulting pseudodielectric function spectra were analyzed using a multilayer approach, describing the dielectric functions of the individual layers by a parametric oscillator model. From this analysis, the dielectric function spectra of GaN, AlxGa1−xN (x≤0.16), and In0.13Ga0.87N were deduced. Further, the dependence of the AlxGa1−xN band gap energy on the Al mole fraction was derived and compared with photoluminescence data recorded on the same material. The SE band gap data are compatible with a bowing parameter close to 1 eV for the composition dependence of the AlxGa1−xN gap energy. Finally, the parametric dielectric functions have been used to model the pseudodielectric function spectrum of a complete GaN/AlGaN/InGaN LED structure.

We report on the composition dependence of the band gap energy of strained hexagonal InxGa1−xN layers on GaN with x≤0.15, grown by metal-organic chemical vapor deposition on sapphire substrates. The composition of the (InGa)N was determined by secondary ion mass spectroscopy. High-resolution X-ray diffraction measurements confirmed that the (InGa)N layers with typical thicknesses of 30 nm are pseudomorphically strained to the in-plane lattice parameter of the underlying GaN. Room-temperature photoreflection spectroscopy and spectroscopic ellipsometry were used to determine the (InGa)N band gap energy. The composition dependence of the band gap energy of the strained (InGa)N layers was found to be given by EG(x)=3.43−3.28 × (eV) for x≤0.15. When correcting for the strain induced shift of the fundamental energy gap, a bowing parameter of 3.2 eV was obtained for the composition dependence of the gap energy of unstrained (InGa)N.

An investigation of the life history of three cohorts of exits based on longitudinal data covering the population of all manufacturing firms in a German federal state reveals three empirical regularities: (1) Although the probability of exit tends to decline with age ceteris paribus, only about a quarter of all exits is from the group of young firms aged five years or less. (2) Only a minor fraction of exits lived through a period of continous decline of employment for five years or more before closing down. (3) The "impact effect" of job loss due to exits can differ sharply from the "long run effect".

We chose synaptic terminals of rat rod bipolar cells as a model system to study activity-related changes in the overall morphology and the fine structure of synaptic sites. Using confocal laser scanning microscopy in conjunction with three-dimensional reconstruction and electron microscopy, we examined the effect of light and dark adaptation on axon terminals identified by protein kinase C (PKC) immunoreactivity. Rod bipolar cell axon terminals consisted of 2-3 polymorphic boutons situated close to the ganglion cell layer and a single ovoid swelling located more distally. Both components of the terminal complex showed adaptation-dependent differences in the distribution of PKC immunoreactivity and in their morphology. In light-adapted rod bipolar cell axon terminals, PKC immunoreactivity was homogeneously distributed throughout the cytoplasm, whereas terminals from dark-adapted animals showed PKC immunoreactivity preferentially localised in the submembrane compartment and a reduced staining of the more central cytoplasm. In three-dimensional reconstructions of optical sections and at the ultrastructural level, the shape of light-adapted axon terminals was round and smooth and exhibited more convexly curved synaptic membranes. In contrast, dark-adapted terminals had irregular contours, numerous dimples and a concave synaptic curvature. No spinules of bipolar cell terminals were observed in dark-adapted material. These observations are discussed in the context of activity-related morphological plasticity of central nervous system synapses and of the functions of PKC in the cycle of vesicle fusion and retrieval at the tonically active ribbon synapses of the rod bipolar axon terminal.

The morphological diversity and dynamic aspects of presynaptic bodies are summarised. Molecular characteristics of the presynaptic machinery are discussed and the signals that control the plasticity of the presynaptic bodies are examined. A review is presented of recent findings regarding the physiology of tonically active synapses. The significance of the synaptic bodies and their dynamic changes in retinal and pineal photoreceptors are considered.

Small firms provide and create a large proportion of jobs in Germany. Are these jobs worse than jobs in larger firms? The mosaic picture that emerges from a review of several recent empirical studies using German individual or firm level micro data shows that, all in all, wages are lower, non-wage incomes (fringes) are lower, job security is lower, work organisation is less rigid, institutionalized possibilities for workers' participation in decision making are weaker, and opportunities for skill enhancement are worse in small firms compared to large firms. The weight of evidence, therefore, indicates that, on average, small firms offer worse jobs than large firms. It is argued that there is no need for policy measures targeted to improve job quality in small firms, because higher incomes in large firms can in part be seen as compensating differentials for more rigid work organisation, and can follow from wage policies to reduce shirking and turnover that is more costly in large than in small firms. Furthermore, a lower level of remuneration, less protection against dismissals, a lower level of workers' participation, and less opportunities for further training all contribute to lower costs in small firms that might be needed to compensate for size-related cost disadvantages compared to large firms. Economic policy should concentrate on keeping barriers to entrepreneurs' entry to markets low to foster new firm formation and creative destruction.

This paper reports new results on the role of firms from various size classes in the job generation process in Germany. It is based on a unique longitudinal data set covering all manufacturing establishments that existed in at least one year between 1978 and 1993 in the German federal state Lower Saxony. We find that gross job creation and destruction rates tend to decline with firm size, while net job creation rates and firm size are not systematically related when firms are classified according to their average number of employees in the base and end year. Small firms create (destroy) quite a large share of all new (lost) jobs. This paper reports new results on the role offirms from various size classes in the job generation processin Germany. It is based on a unique longitudinal data setcovering all manufacturing establishments that existed in atleast one year between 1978 and 1993 in the German federalstate Lower Saxony. We find that gross job creation anddestruction rates tend to decline with finaa size, while net jobcreation rates and firm size are not systematically related whenfirms are classified according to their average number ofemployees in the base and end year. Small firms create(destroy) quite a large share of all new (lost) jobs.

This paper explores the relationships between exports, firm size, and firm dynamics. It is based on a unique longitudinal data set collected at the establishment level, covering some 7000 manufacturing German firms. We present stylized facts on exports and firm size, showing that the probability that a firm is an exporter increases with firm size; however, there are many successful exporters among small firms, and non-exporters among larger firms, too, while most of the exports are from the top size groups of firms. An econometric study shows a picture that is consistent with theoretical considerations: The impact of firm size on exports is positive but decreasing, while human capital intensity, domestic market share, and advanced technology all have a positive influence on the export performance of a firm. Firm growth and export performance are positively related, as is expected from a model of a price-discriminating monopolist. This paper explores the relationships betweenexports, firm size, and firm dynamics. It is based on a uniquelongitudinal data set collected at the establishment level,covering some 7000 manufacturing German firms. We presentstylized facts on exports and firm size, showing that theprobability that a firm is an exporter increases with firm size;however, there are many successful exporters among smallfirms, and non-exporters among larger firms, too, while mostof the exports are from the top size groups of firms. Aneconometric study shows a picture that is consistent withtheoretical considerations: The impact of firm size on exportsis positive but decreasing, while human capital intensity,domestic market share, and advanced technology all have apositive influence on the export performance of a firm. Firmgrowth and export performance are positively related, as isexpected from a model of a price-discriminating monopolist.

This paper implements Freeman’s suggestion that insights into the effect of U.S. unionism on R&D investment may be obtained by correlating U.S. union density by industry with R&D investment by industry in another country, here Germany.

This study is the first attempt to investigate the influence of unions on innovative activities in Germany at the industry level. Econometric models estimated by a highly robust method and submitted to a number of specification tests indicate that trade unions do not have a negative impact on innovative activity which is measured by either the percentage of revenues spent on R&D or the percentage of employees working in R&D. This finding is consistent with evidence on the influence of unions on productivity in Germany and with considerations about the German system of industrial relations.