Search results for "SIP"
showing 10 items of 1280 documents
Unified thermodynamic framework for nonlocal/gradient continuum theories
2003
Abstract A thermodynamic framework, equipped with the concept of nonlocality (energy) residual, is utilized to address nonlocal/gradient internal variable material models. A unified procedure is provided for either nonlocal and gradient materials, which makes it possible to determine the thermodynamic restrictions upon the constitutive equations, and in particular the pertinent state equations, the consistent form of the dissipation power and the constitutive expression of the nonlocality residual. Additionally, for gradient models, the associated nonstandard boundary conditions are derived, pointing out their basically constitutive nature and their substantial differences from the standard…
Water mites of small boreal forest lakes (Central Finland)
1999
The water mite fauna of 10 small forest lakes in close proximity to each other was studied in 1979–1985. In total approximately 62 species of water mites belonging to 22 genera were detected in the lakes. The most diverse genera were Piona (14 species), Arrenurus (11), Unionicola (4) and Limnesia (4). Widely spread and abundant species were Piona variabilis and Limnesia maculata. Locally abundant were Unionicola crassipes, U. minor, Piona carnea and P. paucipora. Zoogeographically interesting though accidental species were Arrenurus werestschagini, Limnesia polonica, Momonia karelica, Piona gyrophora and Unionicola parvipora. Considerable spatial and seasonal differences were observed in th…
Non-Gaussian correlations imprinted by local dephasing in fermionic wires
2020
We study the behavior of an extended fermionic wire coupled to a local stochastic field. Since the quantum jump operator is Hermitian and quadratic in fermionic operators, it renders the model soluble, allowing investigation of the properties of the non-equilibrium steady-state and the role of dissipation-induced fluctuations. We derive a closed set of equations of motion solely for the two-point correlator; on the other hand, we find, surprisingly, that the many-body state exhibits non-Gaussian correlations. Density-density correlation function demonstrates a crossover from a regime of weak dissipation characterized by moderate heating and stimulated fluctuations to a quantum Zeno regime r…
Celebrities' Memorial Afterlives: Obituaries, Tributes, and Posthumous Gossip in the Romanian Media Deathscape.
2017
Cross-culturally, dead are protected from posthumous negative evaluations by the universal “nil nisi bonum” precept that governs the ethics within the community of mourners. In this study, we set out to test the observance of this injunction against posthumous gossiping in the Romanian public deathscape. Obituaries and other posthumous articles ( N = 1,148) were collected that covered the deaths of 63 celebrities who passed away between 2013 and 2016. Materials were gathered from the digital archives of three Romanian news sources (a news agency, a “quality” newspaper, and a tabloid), published one week after the moment of death. The findings show that 22% of the articles do contain negati…
Computational general relativistic force-free electrodynamics
2021
Scientific codes are an indispensable link between theory and experiment; in (astro-)plasma physics, such numerical tools are one window into the universe's most extreme flows of energy. The discretization of Maxwell's equations - needed to make highly magnetized (astro)physical plasma amenable to its numerical modeling - introduces numerical diffusion. It acts as a source of dissipation independent of the system's physical constituents. Understanding the numerical diffusion of scientific codes is the key to classify their reliability. It gives specific limits in which the results of numerical experiments are physical. We aim at quantifying and characterizing the numerical diffusion propert…
The damped harmonic oscillator in deformation quantization
2005
We propose a new approach to the quantization of the damped harmonic oscillator in the framework of deformation quantization. The quantization is performed in the Schr\"{o}dinger picture by a star-product induced by a modified "Poisson bracket". We determine the eigenstates in the damped regime and compute the transition probability between states of the undamped harmonic oscillator after the system was submitted to dissipation.
Quantum transport and the phase space structure of the Wightman functions
2019
We study the phase space structure of exact quantum Wightman functions in spatially homogeneous, temporally varying systems. In addition to the usual mass shells, the Wightman functions display additional coherence shells around zero frequency $k_0=0$, which carry the information of the local quantum coherence of particle-antiparticle pairs. We find also other structures, which encode non-local correlations in time, and discuss their role and decoherence. We give a simple derivation of the cQPA formalism, a set of quantum transport equations, that can be used to study interacting systems including the local quantum coherence. We compute quantum currents created by a temporal change in a par…
Non-equilibrium dynamics of a scalar field with quantum backreaction
2021
We study the dynamical evolution of coupled one- and two-point functions of a scalar field in the 2PI framework at the Hartree approximation, including backreaction from out-of-equilibrium modes. We renormalize the 2PI equations of motion in an on-shell scheme in terms of physical parameters. We present the Hartree-resummed renormalized effective potential at finite temperature and critically discuss the role of the effective potential in a non-equilibrium system. We follow the decay and thermalization of a scalar field from an initial cold state with all energy stored in the potential, into a fully thermalized system with a finite temperature. We identify the non-perturbative processes of …
Noncommutative space and the low-energy physics of quasicrystals
2008
We prove that the effective low-energy, nonlinear Schroedinger equation for a particle in the presence of a quasiperiodic potential is the potential-free, nonlinear Schroedinger equation on noncommutative space. Thus quasiperiodicity of the potential can be traded for space noncommutativity when describing the envelope wave of the initial quasiperiodic wave.
Modified post-bifurcation dynamics and routes to chaos from double-Hopf bifurcations in a hyperchaotic system
2012
In order to understand the onset of hyperchaotic behavior recently observed in many systems, we study bifurcations in the modified Chen system leading from simple dynamics into chaotic regimes. In particular, we demonstrate that the existence of only one fixed point of the system in all regions of parameter space implies that this simple point attractor may only be destabilized via a Hopf or double Hopf bifurcation as system parameters are varied. Saddle-node, transcritical and pitchfork bifurcations are precluded. The normal form immediately following double Hopf bifurcations is constructed analytically by the method of multiple scales. Analysis of this generalized double Hopf normal form …