Search results for " function"
showing 10 items of 9395 documents
Numerical Simulation of Thermal Effects in Electric Circuits via Energy Transport equations
2006
In this work we present the coupling of stationary energy-transport (ET) equations with Modified Nodal Analysis (MNA)-equations to model electric circuits containing semiconductor devices. The one-dimensional ET-equations are discretised in space by an exponential fitting mixed hybrid finite element approach to ensure current continuity and positivity of charge carriers. The discretised ET-equations are coupled to MNA-equations and the resulting system is solved with backwarddifference formulas. Numerical examples are shown for a test circuit containing a pn-diode, and the results are compared to those achieved using the drift-diffusion model to describe the semiconductor devices in the cir…
Non-Markovian master equation for the XX central spin model
2008
The non-Markovian correlated projection operator technique is applied to the model of a central spin coupled to a spin bath through non uniform XX Heisenberg coupling. The second order results of the Nakajima-Zwanzig and of the time-convolutionless methods are compared with the exact solution considering a fully polarized initial bath state.
Nodes of entangledN-particle wave functions
2006
In a recent paper [Bressanini et al. Phys. Rev. Lett. 95, 110201 (2005)] it was pointed out that ``the nodes of even simple wave functions are largely unexplored.'' Here we show that for $N$-particle wave functions nodal surfaces arise from the spin and orbital entanglement of constituent two-particle wave functions and derive, for two-electron atoms, 11 exact nodal rules applicable in $LS$ coupling. In addition, the ``higher symmetry'' identified numerically in the above paper is shown to be an approximate dynamical symmetry described by a molecular model or a classical unstable periodic orbit. We show that the analysis is readily extended to four-particle wave functions and consider the c…
Influence of spatial delay on the modulational instability in a composite system with a controllable nonlinearity.
2017
A theoretical investigation of the modulational instability (MI) in a composite system with a nonlocal response function is presented. A composite system of silver nanoparticles in acetone is chosen, whose nonlinearity can be delicately varied by controlling the volume fraction of the constituents, thus enabling the possibility of nonlinearity management. A pump-probe counterpropagation configuration has been assumed, and the interplay between the competing nonlinearities and the nonlocalities in the MI dynamics is systematically explored. A different class of nonlocalities have been considered, and the study reveals that the nonlocality critically depends on the kind of nonlocal function. …
The electron gas with a strong pairing interaction: Three particle correlations and the Thouless instability
2000
We derive simplified Faddeev type equations for the three particle T-matrix which are valid in the Hubbard model where only electrons with opposite spins interact. Using the approximation of dynamical mean field theory these equations are partially solved numerically for the attractive Hubbard model. It is shown that the three particle T-matrix contains a term vanishing $\sim T^2$ at the Thouless (or BCS) instability where the two-particle T-matrix diverges. Based on the three particle term we further derive the low density - strong coupling extension for the two-particle vertex function. We therefore understand our equations as a step towards a systematic low density expansion from the wea…
Autonomie e controlli della Corte dei conti nel quadro dei principi costituzionali e dei vincoli sovranazionali in materia economico-finanziaria
2022
Una riflessione dei controlli sulle autonomie territoriali intestati alla Corte dei conti non può prescindere dal loro inquadramento costituzionale. L’A. prospetta una ricostruzione del controllo come espressione di una funzione neutra e imparziale che deve riposare su precisi parametri costituzionali che ne legittimano l’adozione e di cui va resa una stretta interpretazione: il controllo sulle Autonomie territoriali deve così essere necessariamente una attività tale da avvicinarla a quella giurisdizionale piuttosto che amministrativa. È in tale chiave che deve essere inteso il rapporto fra ausiliarietà di cui all’art. 100 Cost. e controlli sui bilanci ed i rendiconti. L’evoluzione del quad…
Functionalization of Graphene with Molecules and/or Nanoparticles for Advanced Applications
2019
Graphene is considered the material of the third millennium, due to its extraordinary electronic and mechanical properties, and due to the possibility to modulate its conductivity, flexibility, elasticity, transparency, and biocompatibility by bottom-up approach. The possibility to gather the proper- ties of graphene and graphene oxide with those of functional moieties or nanoparticles is herein reviewed. The synthetic approaches proposed, either covalent or noncovalent, are aimed to tune appropriately graphene’s properties for the realization of materials for advanced uses, such as bio- medical applications, sensors, catalysis, and energy devices. In particular, methods based on covalent l…
Ray-Space-Based Multichannel Nonnegative Matrix Factorization for Audio Source Separation
2021
Nonnegative matrix factorization (NMF) has been traditionally considered a promising approach for audio source separation. While standard NMF is only suited for single-channel mixtures, extensions to consider multi-channel data have been also proposed. Among the most popular alternatives, multichannel NMF (MNMF) and further derivations based on constrained spatial covariance models have been successfully employed to separate multi-microphone convolutive mixtures. This letter proposes a MNMF extension by considering a mixture model with Ray-Space-transformed signals, where magnitude data successfully encodes source locations as frequency-independent linear patterns. We show that the MNMF alg…
Measuring Spatiotemporal Dependencies in Bivariate Temporal Random Sets with Applications to Cell Biology
2008
Analyzing spatiotemporal dependencies between different types of events is highly relevant to many biological phenomena (e.g., signaling and trafficking), especially as advances in probes and microscopy have facilitated the imaging of dynamic processes in living cells. For many types of events, the segmented areas can overlap spatially and temporally, forming random clumps. In this paper, we model the binary image sequences of two different event types as a realization of a bivariate temporal random set and propose a nonparametric approach to quantify spatial and spatiotemporal interrelations using the pair correlation, cross-covariance, and the Ripley K functions. Based on these summary st…
Renal and hepatic integrity in long-term sevoflurane sedation using the anesthetic conserving device: A comparison with intravenous propofol sedation…
2015
Abstract Introduction Critically ill patients are sedated with intravenous agents because the use of inhaled agents is limited by their potential risk of toxicity. Increasing levels of inorganic fluorides after the metabolism of these agents have been considered potentially nephrotoxic. However, hepatic involvement after prolonged administration of sevoflurane has not yet been studied. The present study evaluated the potential renal and hepatic toxicity caused by prolonged administration (72 h) of sevoflurane. Methods For this experimental, prospective, randomized, controlled trial, 22 Landrace × Large-White female pigs were randomly assigned to two groups: intravenous propofol (P) or inhal…