Search results for "SAF"
showing 10 items of 2183 documents
Fluid membranes and2dquantum gravity
2011
We study the RG flow of two dimensional (fluid) membranes embedded in Euclidean D-dimensional space using functional RG methods based on the effective average action. By considering a truncation ansatz for the effective average action with both extrinsic and intrinsic curvature terms we derive a system of beta functions for the running surface tension, bending rigidity and Gaussian rigidity. We look for non-trivial fixed points but we find no evidence for a crumpling transition at $T\neq0$. Finally, we propose to identify the $D\rightarrow 0$ limit of the theory with two dimensional quantum gravity. In this limit we derive new beta functions for both cosmological and Newton's constants.
Flow equation of quantum Einstein gravity in a higher-derivative truncation
2002
Motivated by recent evidence indicating that Quantum Einstein Gravity (QEG) might be nonperturbatively renormalizable, the exact renormalization group equation of QEG is evaluated in a truncation of theory space which generalizes the Einstein-Hilbert truncation by the inclusion of a higher-derivative term $(R^2)$. The beta-functions describing the renormalization group flow of the cosmological constant, Newton's constant, and the $R^2$-coupling are computed explicitly. The fixed point (FP) properties of the 3-dimensional flow are investigated, and they are confronted with those of the 2-dimensional Einstein-Hilbert flow. The non-Gaussian FP predicted by the latter is found to generalize to …
Critical reflections on asymptotically safe gravity
2020
Asymptotic safety is a theoretical proposal for the ultraviolet completion of quantum field theories, in particular for quantum gravity. Significant progress on this program has led to a first characterization of the Reuter fixed point. Further advancement in our understanding of the nature of quantum spacetime requires addressing a number of open questions and challenges. Here, we aim at providing a critical reflection on the state of the art in the asymptotic safety program, specifying and elaborating on open questions of both technical and conceptual nature. We also point out systematic pathways, in various stages of practical implementation, towards answering them. Finally, we also take…
Running Immirzi Parameter and Asymptotic Safety
2011
We explore the renormalization group (RG) properties of quantum gravity, using the vielbein and the spin connection as the fundamental field variables. We require the effective action to be invariant under the semidirect product of spacetime diffeomorphisms and local frame rotations. Starting from the corresponding functional integral we review the construction of an appropriate theory space and an exact funtional RG equation operating on it. We then solve this equation on a truncated space defined by a three parameter family of Holst-type actions which involve a running Immirzi parameter. We find evidence for the existence of an asymptotically safe fundamental theory. It is probably inequi…
Nanomaterial-based biosensors for detection of pathogenic virus
2020
Viruses are real menace to human safety that cause devastating viral disease. The high prevalence of these diseases is due to improper detecting tools. Therefore, there is a remarkable demand to identify viruses in a fast, selective and accurate way. Several biosensors have been designed and commercialized for detection of pathogenic viruses. However, they present many challenges. Nanotechnology overcomes these challenges and performs direct detection of molecular targets in real time. In this overview, studies concerning nanotechnology-based biosensors for pathogenic virus detection have been summarized, paying special attention to biosensors based on graphene oxide, silica, carbon nanotub…
Comparing the cycling behaviours of Australian, Chinese and Colombian cyclists using a behavioural questionnaire paradigm.
2020
Cyclists are vulnerable road users and face disproportionately high rates of road trauma, especially in low- and middle-income countries. Behaviour of road users is a system outcome, and thus studying cyclist behaviours can identify problems in the whole road transport system and assist in generating long-lasting, cost-effective solutions to promote cyclist safety. This study aims to investigate the similarities and disparities of cycling behaviour among countries with different income levels and cycling prevalence, and the relationships among cyclist demographic characteristics, behaviours and crash involvement. It applies the Cycling Behaviour Questionnaire (CBQ) to measure the behaviour …
Increasing Cold Tolerance of Cactus Pear Fruit by High-Temperature Conditioning and Film Wrapping
2017
Pre-storage high-temperature conditioning (HTC, 38 °C, and 95% RH for 24 h) and individual film wrapping (IFW) with a perforated polyolefinic heat-shrinkable film were used as individual treatments or in combination to mitigate chilling injury of first crop cactus pear cv âGiallaâ. The fruit was stored for 21 days at either 2 or 8 °C (CS) plus 1 week of simulated marketing conditions (SMC) at 20 °C. The reduction in peel disorders and decay in HTC-treated fruit stored at 2 °C was comparable to that detected in control fruit stored at 8 °C. IFW was more efficient than HTC in reducing peel disorders, almost completely inhibited weight loss, and preserved freshness in fruit st…
Fire Safety in Historical Theatres (Italian-Style)
2019
The research starts from a punctual knowledge of the theatrical typology under many aspects and in-depth analysis: from the recognition of the monumental value and qualification of a historical theater, collective heritage to be preserved for future generations, we’ll investigate environmental, typological, distributive, functional, material and constructive characters in the earliest designing phases and after the adjustment and transformation interventions occurred. The main aim is identifying all the parts that are at risk of fire, the equipment implementation done to lower such a risk, with the purpose of suggesting adequate systems intended to gain a major level of fire protection in a…
Analysis of a Station Black-Out transient in SMR by using the TRACE and RELAP5 code
2014
The present paper deals with the investigation of the evolution and consequences of a Station Black-Out (SBO) initiating event transient in the SPES3 facility [1]. This facility is an integral simulator of a small modular reactor being built at the SIET laboratories, in the framework of the R&D program on nuclear fission funded by the Italian Ministry of Economic Development and led by ENEA. The SBO transient will be simulated by using the RELAP5 and TRACE nodalizations of the SPES3 facility. Moreover, the analysis will contribute to study the differences on the code predictions considering the different modelling approach with one and/or three-dimensional components and to compare the capa…
RELAP5-3D thermal hydraulic analysis of the target cooling system in the SPES experimental facility
2014
The SPES (Selective Production of Exotic Species) experimental facility, under construction at the Italian National Institute of Nuclear Physics (INFN) Laboratories of Legnaro, Italy, is a second generation Isotope Separation On Line (ISOL) plant for advanced nuclear physic studies. The UCx target-ion source system works at temperature of about 2273 K, producing a high level of radiation (10^5 Sv/h), for this reason a careful risk analysis for the target chamber is among the major safety issues. In this paper, the obtained results of thermofluid-dynamics simulations of accidental transients in the SPES target cooling system are reported. The analysis, performed by using the RELAP5-3D 2.4.2 …