When does lumpy factor adjustment matter for aggregate dynamics?

We analyze the dynamic e¤ects of lumpy factor adjustments at the firm level onto the aggregate economy. We find that distinguishing between capital and labour as lumpy factors within the production function result in very dfferent dynamics for aggregate output, investment and labour in an otherwise standard real business cycle model. Lumpy capital leaves the RBC mainly unchanged, while lumpy labour allows for persistence and an inner propagation within the model in form of hump-shaped impulse repsonses. In addition, when modeling lumpy adjustments on both investment and labour, the aggregate effects are even stronger. We investigate the mechanisms underlying these results and identify the elasticity of factor supply as the most important element in accounting for these differences. JEL Classification: E32, E22, E24business cycles, Elasticity of, Lumpy investment, Lumpy labor adjustment

Macroeconomic implications of downward wage rigidities

Growth of wages, unemployment, employment and vacancies exhibit strong asymmetries between expansionary and contractionary phases. In this paper we analyze to what degree downward wage rigidities in the bargaining process affect other variables of the economy. We introduce asymmetric wage adjustment costs in a New-Keynesian DSGE model with search and matching frictions in the labor market. We find that the presence of downward wage rigidities strongly improves the fit of the model to the skewness of variables and the relative length of expansionary and contractionary phases even when detrending the data. Due to the asymmetry, wages increase more easily in expansions, which limits vacancy posting and employment creation, similar to the flexible wage case. During contractions nominal wages decrease slowly, shifting the main burden of adjustment to employment and hours worked. The asymmetry also explains the differing transmission of positive and negative demand shocks from wages to inflation. Downward wage rigidities help explaining the asymmetric business cycle of many OECD countries where long and smooth expansions with low growth rates are followed by sharp but short recessions with large negative growth rates. JEL Classification: E31, E52, C61asymmetric adjustment costs, downward wage rigidity, Labor market, non—linear dynamics, Unemployment

Essays on Innovations, Technology and the Labor Market.

no abstract availableLabor market; Technological innovations;

A monetary policy strategy in good and bad times: lessons from the recent past

We evaluate the ECB’s monetary policy strategy against the underlying economic structure of the euro area economy, in normal times and in times of severe financial dislocations. We show that in the years preceding the financial crisis that started in 2007 the strategy was successful at ensuring macroeconomic stability and steady growth despite shocks to the supply side and to the transmission mechanism which complicated the policy process. Emphasis on monetary indicators in the ECB’s monetary policy strategy – the monetary pillar – was instrumental in avoiding more volatile and less predictable patterns of inflation and growth. After the collapse of financial intermediation in late 2008, the strategy of the ECB was to preserve the integrity of the monetary policy transmission mechanism by adopting a comprehensive package of non-standard policy measures. According to our quantitative evaluation of the impact of the non-standard policy package, which notably did not include entering commitments regarding the future path of the policy rate, the liquidity interventions decided in October 2008 and in May 2009 were critical to preserving price stability and forestalling a more disruptive collapse of the macro-economy. JEL Classification: E31, E44, E51, E58credit, financial crisis, monetary policy, monetary transmission, Non-standard policy measures, Supply factors

Photon-Management in Dünnschicht-Solarzellen

In dieser Arbeit wurden Maßnahmen vorgestellt, die die Ausbreitung des einfallenden Lichtes innerhalb von Dünnschichtsolarzellen derart modifizieren, dass dadurch deren Wirkungsgrad gesteigert wird. Die Stärke der vorgestellten numerischen Untersuchungen liegt dabei in der rigorosen Lösung der Maxwellschen Gleichungen, welche die Analyse realer Systeme ohne Approximationen erlaubt. Um allgemeine Aussagen treffen zu können, wurde die Simulation der elektronischen Prozesse unterlassen, weil ansonsten eine zu starke Fokussierung auf eine konkrete Solarzelle zu befürchten wäre. In der vorliegenden Arbeit konnten fundamentale Aussagen bezüglich der Ausgestaltung einer idealen Textur getroffen werden, welche für gegenwärtige Dünnschichtsolarzellen über den gesamten relevanten Spektralbereich sowohl Reflexionsverluste unterdrückt als auch zu einer Verlängerung des effektiven Weges führt. Gegenstand der Arbeit war auch der Entwurf eines spektral- und winkelselektiven Filters, der den Akzeptanzwinkel einer Solarzelle mit dem Ziel einer verbesserten Absorption im langwelligen Spektralbereich einschränkt. Hierfür konnte erstmals eine Struktur vorgeschlagen werden, die theoretisch eine Steigerung des Wirkungsgrades erlaubt. Im weiteren Verlauf wurden auch Tandemzellen auf der Basis von amorphem und mikrokristallinem Silizium untersucht. Bei diesen ist die Implementierung eines Zwischenreflektors ein probates Mittel zur Steigerung des Wirkungsgrades. In diesem Zusammenhang wurde die Verwendung von metallischen Nanopartikeln zur Realisierung der gewünschten spektral selektiven Reflektivität angeregt. Des Weiteren konnte auch gezeigt werden, dass sich die Vorzüge von texturierten Oberflächen mit dem Konzept der Zwischenreflektoren vereinen und in Kombination beider Maßnahmen höhere Wirkungsgrade erzielen lassen, als wenn nur eine dieser Komponenten implementiert ist

Gitter für die interferometrische Gravitationswellendetektion

Für das Gravitationswellendetektionsprojekt Geo 600 bei Hannover erwartet man höhere Empfindlichkeiten bei Verwendung diffraktiver Strukturen. In der vorliegenden Arbeit wurde ein Strahlteiler auf Basis eines reflektierenden Gitters designt, hergestellt und vermessen. Ein besonderer Schwerpunkt bestand darin, die Gitterparameter so zu wählen, dass Abweichungen von ihnen auf Grund eines nicht exakt kontrollierbaren Herstellungsprozesses nur geringe Auswirkungen im Experiment zur Folge haben

Modeling the Release Kinetics of Poorly Water-Soluble Drug Molecules from Liposomal Nanocarriers

Liposomes are frequently used as pharmaceutical nanocarriers to deliver poorly water-soluble drugs such as temoporfin, cyclosporine A, amphotericin B, and paclitaxel to their target site. Optimal drug delivery depends on understanding the release kinetics of the drug molecules from the host liposomes during the journey to the target site and at the target site. Transfer of drugs in model systems consisting of donor liposomes and acceptor liposomes is known from experimental work to typically exhibit a first-order kinetics with a simple exponential behavior. In some cases, a fast component in the initial transfer is present, in other cases the transfer is sigmoidal. We present and analyze a theoretical model for the transfer that accounts for two physical mechanisms, collisions between liposomes and diffusion of the drug molecules through the aqueous phase. Starting with the detailed distribution of drug molecules among the individual liposomes, we specify the conditions that lead to an apparent first-order kinetic behavior. We also discuss possible implications on the transfer kinetics of (1) high drug loading of donor liposomes, (2) attractive interactions between drug molecules within the liposomes, and (3) slow transfer of drugs between the inner and outer leaflets of the liposomes

A monetary policy strategy in good and bad times: lessons from the recent past

We evaluate the ECB’s monetary policy strategy against the underlying economic structure of the euro area economy, in normal times and in times of severe financial dislocations. We show that in the years preceding the financial crisis that started in 2007 the strategy was successful at ensuring macroeconomic stability and steady growth despite shocks to the supply side and to the transmission mechanism which complicated the policy process. Emphasis on monetary indicators in the ECB’s monetary policy strategy – the monetary pillar – was instrumental in avoiding more volatile and less predictable patterns of inflation and growth. After the collapse of financial intermediation in late 2008, the strategy of the ECB was to preserve the integrity of the monetary policy transmission mechanism by adopting a comprehensive package of non-standard policy measures. According to our quantitative evaluation of the impact of the non-standard policy package, which notably did not include entering commitments regarding the future path of the policy rate, the liquidity interventions decided in October 2008 and in May 2009 were critical to preserving price stability and forestalling a more disruptive collapse of the macro-economy

Lasers that operate independently of temperature.

Apparatus, methods, systems and devices for providing a temperature independent laser by determining a temperature dependence of a lasing wavelength, selecting the lasing wavelength having minimal temperature dependence and constraining the lasing wavelength of the laser device to the selected lasing wavelength. In an embodiment, a volumetric Bragg grating in photo-thermal refractive glass is used as a laser cavity mirror for constraining the laser emission at the selected wavelength. The laser device may be a broad spectrum laser such as an Er.sup.3+ doped glass broad spectrum laser. In an embodiment, the lasers are operated where the temperature dependence of the stimulated emission cross section is used to compensate for temperature dependent changes of other laser components

Quest for robust optimal macroprudential policy

Este artículo propone una nueva aproximación al análisis de las políticas macroprudenciales basado en el bienestar de la economía. En línea con Gerba (2017), fijamos una función de bienestar con criterios de primer y segundo orden ligados a la utilidad agregada de la economía para determinar los beneficios de distintas reglas macroprudenciales en la zona del euro. Esta propuesta es evaluada en el marco del modelo de Crec et al. (2015). Los resultados muestran que el nivel de capital óptimo es de un 15,6 %, 2,4 puntos porcentuales por encima de la media del período 2001-2015. Situándose los requisitos de capital en su nivel óptimo se reduce signifi cativamente la volatilidad de la economía, a la vez que aumenta el nivel de bienestar a largo plazo, aun siendo un instrumento invariante en el tiempo. Dicho de otro modo, bajo el nivel óptimo de capital el porcentaje de quiebras bancarias hubiera sido 3,5 puntos porcentuales menor, y el crédito y el PIB, un 5 % y un 0,8 % mayores respectivamente, durante la crisis de 2011-2013. Además, con el uso de una función de pérdidas consistente con el modelo, encontramos que la regla para el colchón de capital contracíclico (CCyB) depende de si la economía se encuentra en su nivel óptimo de capital o no. Condicionado a esto último, los resultados sugieren que el CCyB óptimo debe responder a movimientos en el crédito y en los diferenciales hipotecarios. Además, las ganancias en términos de bienestar resultan mayores cuando la determinación de ambas herramientas macroprudenciales es conjunta gracias a las sinergias que se generan.This paper contributes by providing a new approach to study optimal macroprudential policies based on economy wide welfare. Following Gerba (2017), we pin down a welfare function based on a fi rst-and second order approximation of the aggregate utility in the economy and use it to determine the merits of different macroprudential rules for Euro Area. With the aim to test this framework, we apply it to the model of Clerc et al. (2015). We fi nd that the optimal level of capital is 15.6 percent, or 2.4 percentage points higher than the 2001-2015 value. Optimal capital reduces signifi cantly the volatility of the economy while increasing somewhat the total level of welfare in steady state, even with a time-invariant instrument. Expressed differently, bank default rates would have been 3.5 percentage points lower while credit and GDP 5% and 0.8% higher had optimal capital level been in place during the 2011-2013 crisis. Further, using a model-consistent loss function, we fi nd that the optimal Countercyclical Capital Buffer (CCyB) rule depends on whether observed or optimal capital levels are already in place. Conditional on optimal capital level, optimal CCyB rule should respond to movements in total credit and mortgage lending spreads. Gains in welfare from optimal combination of instruments is higher than the sum of their individual effects due to synergies and positive mutual spillovers