Nanolithography and manipulation of graphene using an atomic force microscope

We use an atomic force microscope (AFM) to manipulate graphene films on a nanoscopic length scale. By means of local anodic oxidation with an AFM we are able to structure isolating trenches into single-layer and few-layer graphene flakes, opening the possibility of tabletop graphene based device fabrication. Trench sizes of less than 30 nm in width are attainable with this technique. Besides oxidation we also show the influence of mechanical peeling and scratching with an AFM of few layer graphene sheets placed on different substrates.Comment: 11 pages text, 5 figure

On the constraints violation in forward dynamics of multibody systems

It is known that the dynamic equations of motion for constrained mechanical multibody systems are frequently formulated using the Newton-Euler’s approach, which is augmented with the acceleration constraint equations. This formulation results in the establishment of a mixed set of partial differential and algebraic equations, which are solved in order to predict the dynamic behavior of general multibody systems. The classical resolution of the equations of motion is highly prone to constraints violation because the position and velocity constraint equations are not fulfilled. In this work, a general and comprehensive methodology to eliminate the constraints violation at the position and velocity levels is offered. The basic idea of the described approach is to add corrective terms to the position and velocity vectors with the intent to satisfy the corresponding kinematic constraint equations. These corrective terms are evaluated as function of the Moore-Penrose generalized inverse of the Jacobian matrix and of the kinematic constraint equations. The described methodology is embedded in the standard method to solve the equations of motion based on the technique of Lagrange multipliers. Finally, the effectiveness of the described methodology is demonstrated through the dynamic modeling and simulation of different planar and spatial multibody systems. The outcomes in terms of constraints violation at the position and velocity levels, conservation of the total energy and computational efficiency are analyzed and compared with those obtained with the standard Lagrange multipliers method, the Baumgarte stabilization method, the augmented Lagrangian formulation, the index-1 augmented Lagrangian and the coordinate partitioning method.The first author expresses his gratitude to the Portuguese Foundation for Science and Technology through the PhD grant (PD/BD/114154/2016). This work has been supported by the Portuguese Foundation for Science and Technology with the reference project UID/EEA/04436/2013, by FEDER funds through the COMPETE 2020 – Programa Operacional Competitividade e Internacionalização (POCI) with the reference project POCI-01-0145-FEDER-006941.info:eu-repo/semantics/publishedVersio

Wie stark wird der Konsum vom Vermögen bestimmt?

Im Euroraum und insbesondere in Deutschland hat sich die Konjunktur lange Zeit nur schwach entwickelt. Ein wesentlicher Grund dafür war nur eine verhaltene Dynamik der Binnennachfrage und insbesondere des Konsums. Im Durchschnitt unterschiedlicher Länder ist ein deutlicher Einfluss der Vermögensmärkte auf die Konsumausgaben nachweisbar. Dabei hat die Bedeutung des Immobilienbesitzes als Vermögenskomponente in den letzten Jahren zugenommen. Pro Euro Vermögenszuwachs werden ungefähr 2 Cent für zusätzlichen Konsum verwendet. Der Vermögenseinfluss ist in Deutschland im Vergleich zu Ländern mit stärker kapitalmarktbasierten Finanzsystemen schwächer ausgeprägt. Bei den Immobilienpreisen ist überhaupt kein Einfluss erkennbar. Dementsprechend lässt sich die Entwicklung in Deutschland auch nicht durch die hierzulande stagnierenden Immobilienpreise erklären. Abstract The economic performance in the euro area and in particular in Germany has been rather weak over the recent past. Despite the cyclical upturn of the world economy domestic demand and private consumption have grown only modestly. The path of private consumption depends on the evolution of financial and housing wealth, where the impact of the latter seems to have risen over the last years. In the aggregate, a wealth increase of 1 euro is expected to trigger private consumption by about 2 cents. However, the impact of wealth is lower in bank than in market based economies. In fact, housing prices do not have any impact on the path of private consumption in bank dominated systems. Therefore, the weak economic performance in Germany could not be explained by the stagnation in housing prices. JEL Klassifikation: E21, E32, C2