Equilibrium and nonequilibrium effects in nucleus nucleus collisions

Abstract: Local thermal and chemical equilibration is studied for central AqA collisions at 10.7 160 AGeV in the Ultrarelativis- . tic Quantum Molecular Dynamics model UrQMD . The UrQMD model exhibits strong deviations from local equilibrium at the high density hadron string phase formed during the early stage of the collision. Equilibration of the hadron resonance matter is established in the central cell of volume Vs125 fm3 at later stages, tG10 fmrc, of the resulting quasi-isentropic expansion. The thermodynamical functions in the cell and their time evolution are presented. Deviations of the UrQMD quasi-equilibrium state from the statistical mechanics equilibrium are found. They increase with energy per baryon and lead to a strong enhancement of the pion number density as compared to statistical mechanics estimates at SPS energies. PACS: 25.75.-q; 24.10.Lx; 24.10.Pa; 64.30.q

Local equilibrium in heavy ion collisions. Microscopic model versus statistical model analysis

The assumption of local equilibrium in relativistic heavy ion collisions at energies from 10.7 AGeV (AGS) up to 160 AGeV (SPS) is checked in the microscopic transport model. Dynamical calculations performed for a central cell in the reaction are compared to the predictions of the thermal statistical model. We find that kinetic, thermal and chemical equilibration of the expanding hadronic matter are nearly approached late in central collisions at AGS energy for t >= 10 fm/c in a central cell. At these times the equation of state may be approximated by a simple dependence P ~= (0.12-0.15) epsilon. Increasing deviations of the yields and the energy spectra of hadrons from statistical model values are observed for increasing energy, 40 AGeV and 160 AGeV. These violations of local equilibrium indicate that a fully equilibrated state is not reached, not even in the central cell of heavy ion collisions at energies above 10 AGeV. The origin of these findings is traced to the multiparticle decays of strings and many-body decays of resonances

Align-RUDDER: Learning From Few Demonstrations by Reward Redistribution

Reinforcement Learning algorithms require a large number of samples to solve complex tasks with sparse and delayed rewards. Complex tasks can often be hierarchically decomposed into sub-tasks. A step in the Q-function can be associated with solving a sub-task, where the expectation of the return increases. RUDDER has been introduced to identify these steps and then redistribute reward to them, thus immediately giving reward if sub-tasks are solved. Since the problem of delayed rewards is mitigated, learning is considerably sped up. However, for complex tasks, current exploration strategies as deployed in RUDDER struggle with discovering episodes with high rewards. Therefore, we assume that episodes with high rewards are given as demonstrations and do not have to be discovered by exploration. Typically the number of demonstrations is small and RUDDER's LSTM model as a deep learning method does not learn well. Hence, we introduce Align-RUDDER, which is RUDDER with two major modifications. First, Align-RUDDER assumes that episodes with high rewards are given as demonstrations, replacing RUDDER's safe exploration and lessons replay buffer. Second, we replace RUDDER's LSTM model by a profile model that is obtained from multiple sequence alignment of demonstrations. Profile models can be constructed from as few as two demonstrations as known from bioinformatics. Align-RUDDER inherits the concept of reward redistribution, which considerably reduces the delay of rewards, thus speeding up learning. Align-RUDDER outperforms competitors on complex artificial tasks with delayed reward and few demonstrations. On the MineCraft ObtainDiamond task, Align-RUDDER is able to mine a diamond, though not frequently. Github: https://github.com/ml-jku/align-rudder, YouTube: https://youtu.be/HO-_8ZUl-U

Mid-infrared Fourier-domain optical coherence tomography with a pyroelectric linear array

Optical technology in the mid-infrared wavelength range is currently a rapidly developing field initiated by the availability of novel high-power and spatially coherent sources. Non-destructive testing techniques based on these sources are very promising for industrial and medical applications. However, there are still many engineering problems due to the technical challenges and high prices of the optical elements suitable for the mid-infrared region. In this paper, we report the development and performances of the first mid-infrared Fourier-domain optical coherence tomography based on a supercontinuum source and low-cost pyroelectric detector. The system is designed to operate in the spectral region around 4?m. Experimental results are demonstrated for detections of embedded microstructures in ceramic materials and subsurface oil paint layers

ISEK⁴ – A Regional Approach to Inner City Development

Integrated planning approaches provide the toolkit for delivering holistic and interdisciplinary solutions to meet the complex challenges of the 21st century. However, established instruments such as the integrated urban development concept (ISEK, common in Germany) lack the multilevel spatial integration required to tackle these issues effectively. Designed as a pilot project for the development of a new planning instrument, ISEK⁴ addressed two spatial spheres that – despite obvious necessity – are rarely considered together in the existing planning toolkit: the inner city and the functional region. Within eight months, integrated urban development concepts for the inner cities of Bruneck (South Tyrol), Hermagor-Pressegger See (Upper Carinthia), Lienz (East Tyrol), and Spittal an der Drau (Upper Carinthia) were developed along with a regional symbiosis of the SOUTH ALPINE SPACE, demonstrating and using synergies between the inner cities as anchor points of public life in the region. The ISEK⁴ project was based on a transdisciplinary planning approach and developed together with local steering groups from the cities. During the project, knowledge and needs were collected, recorded, and spatially contextualized in different workshop settings. In the work process, a mixed methods approach comprised of qualitative (GIS accessibility analyses, heat mapping) and qualitative (visioneering, storytelling, document analysis, design thinking lab, etc.) planning and research methods was employed. The central outcome of the ISEK⁴ project was a joint regional vision of the future, in both which local potentials and characteristics as well as regional strategies for action are represented. Alongside a geographically warped future image of the region, a vision story was used to outline the key areas of joint action. The ISEK⁴ concept also contains four city-specific sections (local ISEKs) drawing upon the so-called regional guiding principles, which are combined in one joint document. The key innovation of the project was the simultaneous consideration of four municipal city centres within a regional framework. It was shown that through the symbiosis of multiple concepts, activities in the field of inner-city development can be bundeled strategically and, in many cases, also implemented together. This paper focuses on the work process, the lessons learned and the transferability of the project approach, as well as selected results. A special focus will be on the methodological aspects of the storytelling method that was employed in the design of the regional and local future visions for ISEK⁴

Extracellular vesicles in human skin: cross-talk from senescent fibroblasts to keratinocytes by miRNAs

Extracellular vesicles (EVs) and their miRNA cargo are intercellular communicators transmitting their pleiotropic messages between different cell types, tissues, and body fluids. Recently, they have been reported to contribute to skin homeostasis and were identified as members of the senescence-associated secretory phenotype of human dermal fibroblasts. However, the role of EV-miRNAs in paracrine signaling during skin aging is yet unclear. Here we provide evidence for the existence of small EVs in the human skin and dermal interstitial fluid using dermal open flow microperfusion and show that EVs and miRNAs are transferred from dermal fibroblasts to epidermal keratinocytes in 2D cell culture and in human skin equivalents. We further show that the transient presence of senescent fibroblast derived small EVs accelerates scratch closure of epidermal keratinocytes, whereas long-term incubation impairs keratinocyte differentiation in vitro. Finally, we identify vesicular miR-23a-3p, highly secreted by senescent fibroblasts, as one contributor of the EV-mediated effect on keratinocytes in in vitro wound healing assays. To summarize, our findings support the current view that EVs and their miRNA cargo are members of the senescence-associated secretory phenotype and, thus, regulators of human skin homeostasis during aging