Search results for "first"
showing 10 items of 1149 documents
Phonon Driven Floquet Matter.
2018
The effect of electron–phonon coupling in materials can be interpreted as a dressing of the electronic structure by the lattice vibration, leading to vibrational replicas and hybridization of electronic states. In solids, a resonantly excited coherent phonon leads to a periodic oscillation of the atomic lattice in a crystal structure bringing the material into a nonequilibrium electronic configuration. Periodically oscillating quantum systems can be understood in terms of Floquet theory, which has a long tradition in the study of semiclassical light-matter interaction. Here, we show that the concepts of Floquet analysis can be applied to coherent lattice vibrations. This coupling leads to p…
Monitoring Electron-Photon Dressing in WSe 2
2016
Optical pumping of solids creates a non-equilibrium electronic structure where electrons and photons combine to form quasiparticles of dressed electronic states. The resulting shift of electronic levels is known as the optical Stark effect, visible as a red shift in the optical spectrum. Here we show that in a pump-probe setup we can uniquely define a non-equilibrium quasiparticle bandstructure that can be directly measurable with photoelectron spectroscopy. The dynamical photon-dressing (and undressing) of the many-body electronic states can be monitored by pump-probe time and angular resolved photoelectron spectroscopy (tr-ARPES) as the photon-dressed bandstructure evolves in time dependi…
Resonant activation in piecewise linear asymmetric potentials
2011
7 páginas, 8 figuras.-- PACS number(s): 05.40.−a, 05.45.−a, 02.50.Ey
Hunger and Food Charity in Rich Societies: What Hope for the Right to Food?
2014
First World Hunger: Food Security and Welfare Politics (Riches, 1997a) offered the first cross-national study of the emergence and entrenchment of food aid and charitable food banking from the early 1980s to the mid-1990s. It consists of five case studies from advanced industrial countries with developed ‘liberal’ welfare states: Australia, Canada, New Zealand, the UK and the USA. All of the countries were food exporters and food secure through national production and imports, suggesting that domestic hunger could not be caused by the failure to provide sufficient food and nutrition, but rather was a matter of distributional justice and human rights — that is a fundamentally political issue.
On the validity of Friedrichs’ inequalities
1984
A standard proof of Friedrich's second inequality is based on contradiction argumentation. In this paper a direct proof is presented. Moreover, necessary and sufficient conditions for the validity of Friedrichs' first and second inequality are given for plane domains. peerReviewed
K-12 game programming course concept using textual programming
2011
Several programming environments have been constructed to facilitate novice programming at K-12 and CS0/CS1 levels. The environments can be roughly divided into those using visual or textual programming. This paper presents a K-12 game programming course concept based on textual programming. The concept is based on an easy-to-use C# library, called Jypeli, built on top of Microsoft XNA Framework. The library tries to maintain advantages of visual programming and avoid challenges of textual programming. In particular, the library helps beginners to program their first games in a short period of time and without a heavy syntactic load. The course concept and an initial evaluation consisting o…
Quantification of resting myocardial blood flow in a pig model of acute ischemia based on first-pass MRI
2005
Qualitative and semiquantitative contrast-enhanced (CE) dynamic perfusion MRI techniques are established as noninvasive diagnostic means of assessing coronary artery disease. However, to date quantification of myocardial blood flow (MBF) has not reached the same acceptance as MBF quantification with nuclear techniques. To validate quantification of MBF at rest using the extracellular contrast agent (CA) Gd-DTPA, we performed an animal study in a pig model of acute myocardial ischemia. We quantified MBF from MRI data with a mathematical model (MMID4) of the underlying vasculature. These MBF results were subsequently compared with the results from fluorescent microspheres. The study showed a …
Player performance, satisfaction, and video game enjoyment
2009
An experiment (N = 74) was conducted to investigate the impact of game difficulty and player performance on game enjoyment. Participants played a First Person Shooter game with systematically varied levels of difficulty. Satisfaction with performance and game enjoyment were assessed after playing. Results are not fully in line with predictions derived from flow and attribution theory and suggest players to (1) change their view on their own performance with its implications for enjoyment with increasing game experience and (2) to switch strategically between different sources of fun, thus maintaining a (somewhat) positive experience even when performance-based enjoyment is low.
Simulation as a game design tool
2009
In this paper we suggest using gameplay simulations on a logical event level as a design tool already in the early stages of the development process. The approach is centred on abstracting all unnecessary details of the gameplay to produce a highly simplified model of the game system. Compared to other kinds of intermediate design representations, such as sketches and prototypes, the simulations can reveal problems and opportunities in the longer term dynamics of possible gameplay. As an example we describe an implementation of a simulation model for the game Tower Bloxx using a simulation software package called DisCo.
PRACTICAL ASPECTS OF THE ANALYSIS OF THE PROGRESSION CURVES OF FIRST AND PSEUDO-FIRST ORDER REACTIONS
2020
The paper presents a simple method of determining iteratively the progression curve asymptote for first and pseudo-first order reactions. For selected student exercises, thus obtained results were compared (see Supplementary Material) with those found by means of the method of determining asymptotes experimentally. A nonlinear fitting method was additionally employed to assess the accuracy.