Spectral, optical and transport properties of the adiabatic anisotropic Holstein model: Application to slightly doped organic semiconductors

Spectral, optical and transport properties of an anisotropic three-dimensional Holstein model are studied within the adiabatic approximation. The parameter regime is appropriate for organic semiconductors used in single crystal based field effect transistors. Different approaches have been used to solve the model: self-consistent Born approximation valid for weak electron-phonon coupling, coherent potential approximation exact for infinite dimensions, and numerical diagonalization for finite lattices. With increasing temperature, the width of the spectral functions gets larger and larger making the approximation of quasi-particle less accurate. On the contrary, their peak positions are never strongly renormalized in comparison with the bare ones. As expected, the density of states is characterized by an exponential tail corresponding to localized states at low temperature. For weak electron-lattice coupling, the optical conductivity follows a Drude behavior, while, for intermediate electron-lattice coupling, a temperature dependent peak is present at low frequency. For high temperatures and low particle densities, the mobility always exhibits a power-law behavior as function of temperature. With decreasing the particle density, at low temperature, the mobility shows a transition from metallic to insulating behavior. Results are discussed in connection with available experimental data.Comment: 9 pages, 7 figures, submitted to Phys. Rev.

Performance evaluation of urban traffic management and ITS: The Rome case study

In order to cope with their growing traffic problems, cities throughout the world deploy Intelligent Transport System (ITS) applications in various fields of urban networks. The decision making process for the installation of ITS is a dialogue between the political instance of the municipalities and the planners. The strategic concept and the detailed planning are undertaken by transportation experts in the respective planning authorities and is based on a vast variety of measurements and evaluations (Reed et al., 1993). The decision for funding the systems however is taken on a political level and is based on the consideration of expected benefits, economic aspects but also public debates and controversies. It is obvious that this dialogue within an inhomogeneous group of stakeholders needs a common basis for the consideration of benefits of ITS as a counterpart to the often obvious costs.In order to deliver this common basis of discussion, a transparent methodology to calculate and present the benefits of ITS has to be elaborated.This methodology should support the decision making process in several aspects:? to identify best practice applications already operational in similar cases in other cities;? to decide on the installation of the system on a technical and a political level;* Technische Universität München† IUAV University of Venice‡ Imperial College London§ Technion, Israel Institute of Technology2. to monitor the performance of the deployed application over a longer period of time;to weigh the investment and operational cost compared to thebenefits of the system. Several solutions to this problem were proposed within the EU FP7 project CONDUITS (2009 - 2011). They included the elaboration of a set of Key Performance Indicators (KPI) targeting different categories of ITS and providing a single, measurable value for their benefit. The following paper gives an overview of the definition process for the KPI, explains their function and gives an example for the calculation of the KPI based on real-life data provided by the city of Rome

Plus forts ensemble - Swiss School of Public Health

De vénérables écoles de santé publique ont fêté leur 100 e anniversaire au cours des 20 dernières années. En Suisse, la pandémie a pris au dépourvu une institution adolescente - un modèle innovant qui fête son 16 e anniversaire cette année. L'âge adulte a-t-il été atteint

Similarities between skin culturable bacterial species of pool frogs (Pelophylax lessonae) and their habitat

The aim of the present study was to investigate the culturable microflora of pool frogs (Pelophylax lessonae) and their belonging aquatic environment. A total of 60 samples (56 frog cutaneous swabs, 4 water samples) were inoculated onto different selective and differential agar plates to isolate Grampositive and Gram-negative bacteria or yeasts. Microbial investigation of the water hosting frogs was also performed. Isolates were identified by API system and their antibiotic resistance profiles were evaluated by disk diffusion method on Mueller Hinton agar plates. Aeromonas hydrophila and Enterococcus durans were detected in almost all collected samples. Many of the bacterial isolates showed multidrug-resistant profiles. Importantly, this study highlights that skin frog microbiota is correlated to the belonging environment, and, moreover, some isolated bacterial strains resulted to be of interest in animal and public health, since the park was frequented by visitors of all ages

Spin chirality on a two-dimensional frustrated lattice

The collective behavior of interacting magnetic moments can be strongly influenced by the topology of the underlying lattice. In geometrically frustrated spin systems, interesting chiral correlations may develop that are related to the spin arrangement on triangular plaquettes. We report a study of the spin chirality on a two-dimensional geometrically frustrated lattice. Our new chemical synthesis methods allow us to produce large single crystal samples of KFe3(OH)6(SO4)2, an ideal Kagome lattice antiferromagnet. Combined thermodynamic and neutron scattering measurements reveal that the phase transition to the ordered ground-state is unusual. At low temperatures, application of a magnetic field induces a transition between states with different non-trivial spin-textures.Comment: 7 pages, 4 figure