Quantum theory of light and noise polarization in nonlinear optics

We present a consistent quantum theory of the electromagnetic field in nonlinearly responding causal media, with special emphasis on $\chi^{(2)}$ media. Starting from QED in linearly responding causal media, we develop a method to construct the nonlinear Hamiltonian expressed in terms of the complex nonlinear susceptibility in a quantum mechanically consistent way. In particular we show that the method yields the nonlinear noise polarization, which together with the linear one is responsible for intrinsic quantum decoherence.Comment: 4 pages, no figure

Zur Diversifizierung der Wohnraumversorgung: Gleichzeitigkeiten von Leerstand und neuer Wohnungsnot

"Konnten wir über das letzte Jahrhundert hinweg Phasen entspannter und angespannter Verhältnisse auf dem Wohnungsmarkt beobachten, die regional kaum variierten und vorwiegend durch Kriege und politische Verwerfungen generiert waren, haben wir es derzeit mit regional sehr unterschiedlichen Wohnungs(teil)märkten zu tun. Wohnungsleerstand und Abrisse prägen die Situation in schrumpfenden Gemeinden vor allem im Osten Deutschlands, während in wenigen prosperierenden Großstädten in Westdeutschland ein dramatischer Wohnungsmangel beklagt wird. Eine Beurteilung der Wohnraumversorgungssituation muss daher diese Disparitäten berücksichtigen und wohnungspolitische Maßnahmen vor diesem Hintergrund relektieren." (Autorenreferat

Europäische Stadt

Unterschiedliche Kulturen, Religionen, Herrschaftssysteme, Ethnien, Ökonomien, Planungen und Projekte haben die Herausbildung von unterschiedlichen Stadtpersönlichkeiten in Europa begünstigt. Gesellschaftlicher Wandel hat die Städte fortwährend verändert und Spuren, Verwerfungen sowie Überlagerungen befördert, die heute europäische Städte kennzeichnen. Städte bilden damit ein Spiegelbild der jeweiligen politischen, rechtlichen und administrativen Gegebenheiten sowie historischer Prozesse von langer Dauer. Mit Eindeutigkeit ist die europäische Stadt an sich nicht zu erfassen

Neue Werkstoffe aus Ton, Faserstoffen und Bindemitteln durch Press- und Aufbauagglomeration

Ausgehend von den Erkenntnissen zu den traditionellen Lehmbaustoffen sollte untersucht werden, ob sich aus tonmineralhaltigen Rohstoffen, Faserstoffen sowie den Bindemitteln Montanwachsreststoff und Braunkohle hochwertige Formkörper und Schüttgüter herstellen lassen. Dabei hatte die Formgebung mit Hilfe von Agglomerationsprozessen ohne nachfolgende Hochtemperaturprozesse zu erfolgen. Die Untersuchungen haben gezeigt, dass eine hohe Produktqualität die Bildung stabiler formschlüssiger Bindungen zwischen den Teilchen des Faserstoffes voraussetzt. Diese lassen sich insbesondere mit sehr schlanken Fasern erzielen, für deren Aufbereitung und Modifizierung sich der Doppelschneckenextruder eignet. Die formschlüssigen Bindungen werden durch den Ton sowie die verwendeten Bindemittel stabilisiert, so dass hohe Produktfestigkeiten und teilweise gute Wasserbeständigkeiten erreicht werden. Außerdem zeichnen sich die hergestellten Produkte durch gute Bearbeitungseigenschaften aus

Molecular wires:impact of π-conjugation and implementation of molecular bottlenecks

In this review we highlight recent progress in the field of photochemically and thermally induced electron transport through molecular bridges as integrative parts of electron donor–bridge–acceptor conjugates. The major emphasis is hereby on the design and the modular composition of the bridges. To this end, we will demonstrate that control over attenuation factors and reorganization energies, on one hand, as well as electronic and electron–vibration couplings, on the other hand, enables tuning electron transport over distances as short as 3.5 Å and as large as 50 Å by up to nine orders of magnitude. In terms of electron transport, the maximum extreme is given by carbon-bridged oligo-p-phenylenevinylenes of different lengths, while a zinc tetraphenylporphyrin free base tetraphenylporphyrin dyad constitutes the minimum extreme

Fullerene van der waals Oligomers as electron traps

Density functional theory calculations indicate that van der Waals fullerene dimers and larger oligomers can form interstitial electron traps in which the electrons are even more strongly bound than in isolated fullerene radical anions. The fullerenes behave like super atoms , and the interstitial electron traps represent one-electron intermolecular σ-bonds. Spectroelectrochemical measurements on a bis-fullerene-substituted peptide provide experimental support. The proposed deep electron traps are relevant for all organic electronics applications in which non-covalently linked fullerenes in van der Waals contact with one another serve as n-type semiconductors

A gradual depth-dependent change of connectivity features of supragranular pyramidal cells in rat barrel cortex

Recent experimental evidence suggests a finer genetic, structural and functional subdivision of the layers which form a cortical column. The classical layer II/III (LII/III) of rodent neocortex integrates ascending sensory information with contextual cortical information for behavioral read-out. We systematically investigated to which extent regular-spiking supragranular pyramidal neurons, located at different depths within the cortex, show different input-output connectivity patterns. Combining glutamate-uncaging with whole-cell recordings and biocytin filling, we revealed a novel cellular organization of LII/III: (i) “Lower LII/III” pyramidal cells receive a very strong excitatory input from lemniscal LIV and much fewer inputs from paralemniscal LVa. They project to all layers of the home column, including a feedback projection to LIV whereas transcolumnar projections are relatively sparse. (ii) “Upper LII/III” pyramidal cells also receive their strongest input from LIV, but in addition, a very strong and dense excitatory input from LVa. They project extensively to LII/III as well as LVa and Vb of their home and neighboring columns, (iii) “Middle LII/III” pyramidal cell show an intermediate connectivity phenotype that stands in many ways in-between the features described for lower versus upper LII/III. “Lower LII/III” intracolumnarly segregates and transcolumnarly integrates lemniscal information whereas “upper LII/III” seems to integrate lemniscal with paralemniscal information. This suggests a finegrained functional subdivision of the supragranular compartment containing multiple circuits without any obvious cytoarchitectonic, other structural or functional correlate of a laminar border in rodent barrel cortex

Disentangling the Effects of Processing Speed on the Association between Age Differences and Fluid Intelligence

Several studies have demonstrated that individual differences in processing speed fully mediate the association between age and intelligence, whereas the association between processing speed and intelligence cannot be explained by age differences. Because measures of processing speed reflect a plethora of cognitive and motivational processes, it cannot be determined which specific processes give rise to this mediation effect. This makes it hard to decide whether these processes should be conceived of as a cause or an indicator of cognitive aging. In the present study, we addressed this question by using a neurocognitive psychometrics approach to decompose the association between age differences and fluid intelligence. Reanalyzing data from two previously published datasets containing 223 participants between 18 and 61 years, we investigated whether individual differences in diffusion model parameters and in ERP latencies associated with higher-order attentional processing explained the association between age differences and fluid intelligence. We demonstrate that individual differences in the speed of non-decisional processes such as encoding, response preparation, and response execution, and individual differences in latencies of ERP components associated with higher-order cognitive processes explained the negative association between age differences and fluid intelligence. Because both parameters jointly accounted for the association between age differences and fluid intelligence, age-related differences in both parameters may reflect age-related differences in anterior brain regions associated with response planning that are prone to be affected by age-related changes. Conversely, age differences did not account for the association between processing speed and fluid intelligence. Our results suggest that the relationship between age differences and fluid intelligence is multifactorially determined