Critical behavior of a non-equilibrium interacting particle system driven by an oscillatory field

First- and second-order temperature driven transitions are studied, in a lattice gas driven by an oscillatory field. The short time dynamics study provides upper and lower bounds for the first-order transition points obtained using standard simulations. The difference between upper and lower bounds is a measure for the strength of the first-order transition and becomes negligible small for densities close to one half. In addition, we give strong evidence on the existence of multicritical points and a critical temperature gap, the latter induced by the anisotropy introduced by the driving field.Comment: 12 pages, 4 figures; to appear in Europhys. Let

Revisiting the nonequilibrium phase transition of the triplet-creation model

The nonequilibrium phase transition in the triplet-creation model is investigated using critical spreading and the conservative diffusive contact process. The results support the claim that at high enough diffusion the phase transition becomes discontinuous. As the diffusion probability increases the critical exponents change continuously from the ordinary directed percolation (DP) class to the compact directed percolation (CDP). The fractal dimension of the critical cluster, however, switches abruptly between those two universality classes. Strong crossover effects in both methods make it difficult, if not impossible, to establish the exact location of the tricritical point.Comment: 7 pages, 12 figure

The Unity of Happiness and Reason in Hegel

In this paper, I discuss the connection between happiness and reason in the work of Herder, Kant, and Hegel. First, I consider Herder’s integration of satisfaction and rationality and Kant’s complete separation of rational imperatives from particular experience. I discuss (and partially endorse) Kant’s critique of Herder as arbitrary and overly reliant on analogy. I then turn to Hegel’s response to this debate. I argue that Hegel’s Phenomenology provides an integration of happiness (in the broad, Aristotelian sense) and reason that is not subject to the same pitfalls as Herder’s solution. I examine two examples of rational critique in the Phenomenology and conclude with brief remarks about happiness and the rational society in Hegel’s work

Scalable dynamic simulation-based methodology for the energy retrofit of existing buildings

It is widely recognized that the building sector largely contributes to the total European energy consumption with a 40% influence on the total assessed energy uses. To this regard the EPBD recast Directive promotes nearly zero energy buildings (nZEB) for the public and the private sector as a mandatory requirement by 2020. Given the low energy efficiency of old buildings, concerns about the state of the existing building stock should be seriously considered as most of the energy consumption is attributable to the existing buildings. Additionally, residential buildings are often seen as long-term assets, setting thus a low replacement rate, approximately 1% per year in Europe, of old buildings by new ones. To this regard, larger energy savings can be achieved with the energy retrofitting of the existing building stock, rather than with the construction of relatively small proportion of new high performing buildings. Therefore, the refurbishment of the existing building stock has to be primarily planned and accomplished in order to achieve a timely reduction on the buildings energy consumption. Concerning this, the EPBD recast, as policy driver for reducing European energy use in buildings, has been representing the first and main legislative reference. According to it Member States must ensure that minimum energy performance requirements are set with a view of achieving at least cost-optimal levels for buildings, building units and building elements” by means of a comparative methodology framework applied to new constructions and existing buildings undergoing major renovations. The methodology specifies how to compare energy efficiency measures in relation to their energy performance and to the cost attributed to their implementation, and how to apply these to selected reference buildings with the aim of identifying cost-optimal levels of minimum energy performance requirements. A cost optimal level is defined as the energy performance level, which leads to the lowest cost during the estimated economic lifecycle of the building. A measure is considered cost-effective when the cost of implementation is lower than the achievable benefits, during the expected life of the measure. This type of analysis allows defining energy renovation scenario based on their energy and economic optimum. Within the complex scenario described above, this Ph.D. thesis aims to provide a scalable methodology for the definition of energy retrofit scenarios to be applied to existing buildings, based on the use of dynamic building simulation models. The methodology targets the existing building stock given the large energy savings that can be achieved from existing buildings. It builds on an energy and economic assessment of energy efficiency measures applied to different building typologies. The energy and economic assessment are respectively carried out by means of dynamic building simulation and a cost-optimality approach. The cost optimal analysis was chosen for the aim of this study for its systematic approach in defining energy retrofit interventions based on their energy and economic optimum. The term “scalable” is used for defining the methodology as the studied energy retrofit scenarios can vary depending on the “scale” of the study. Two main scales of buildings can be distinguished: building stock or single buildings. When retrofit interventions are studied to be applied to wide portion of the building stock, as for example at national level, representative building models are used. They correspond to reference buildings representative of a certain building typology, construction age and geographic location. Within this thesis, a methodology for their definition was defined and various reference buildings for the Italian context were created. On the contrary, when it is necessary to study specific and customized retrofit measures, a single existing building is modelled. In this case, compared to the case of the reference buildings, larger quantity of data and a higher degree of detail are necessary. These building models are customized based on the existing buildings characterization (e.g. building envelope, system, etc) and when applicable, based also on data from monitoring. To this regards, when detailed information about the building real operation from monitoring is available, the building model need to be calibrated based on measured data. For a model to be calibrated, the building energy consumption predicted by the simulation program, has to match the consumption measured from monitoring. Calibrated models can be used for comparing the baseline situation of the building (calibrated and not retrofitted) with other simulation results relative to the application of building renovation interventions. To this regard, within this Ph.D. thesis, a literature review on the most common calibration techniques currently in use for the calibration of building models was conducted. Additionally two case studies were calibrated by means of two different approaches: a trial and error approach and an optimization-based calibration. For both scale of buildings (building stock and single buildings), dynamic building simulation was employed for the energy assessment. Building simulation application has expanded since mid-‘70s building simulation as an attempt to emulate reality. To date, it is much more common to employ building simulation in post construction or advanced building design phases rather than in early phases. In particular building simulation is frequently used for the prediction of energy savings by assessing energy retrofit interventions on existing buildings. To this regard, given its wide application and the high level of detail of the analysis performed (dynamic analysis), building simulation was chosen within this thesis, as a tool for the energy assessment of buildings and of the relative energy renovation interventions. Finally, the economic assessment of the energy retrofit measures was carried out by means of the cost optimal methodology, as defined by the EPBD recast. The methodology allowed defining energy renovation interventions based on their economical and energy optimum. The Directive requires to define different packages of energy efficiency measures, which can be applied to reference representative buildings but also to single and existing building for energy and economical assessments. The energy assessment of a building can be carried out with analytical or simplified methods, but dynamic building simulation is strongly suggested, as performed within this thesis. For the economic assessment, the global cost method was employed based on the calculation method of the Standard EN 15459 as advised by the EBPD. The global cost method considers, for each energy efficiency measure, the initial investment, the sum of the annual costs for every year (including energy costs) and the final value, all with reference to the starting year of the calculation period. In order to define different energy retrofit solution and set the minimum energy performance requirements, within the Ph.D. thesis, the cost optimal approach was applied to both the considered scale of buildings: to the building stock scale with three reference buildings, and to the single buildings scale with two calibrated buildings. A set of energy efficiency measures was defined and applied to the case studies for evaluating the financial and energy performance gap between the cost-optimal solutions and nZEB levels, respectively. For the building stock, different energy retrofit solutions are defined as final outcomes. Given the use of representative models (reference buildings), the retrofit solutions can be replicated to several buildings, among the same building typology. In this sense, different energy retrofit solutions can be established. On the other hand, for single buildings, the energy retrofit solution studied is specific and customized barely to the analyzed case study

Rôle des canaux ionique dans la mort cellulaire induit par stress osmotique

The work presented in the present thesis relates to the role of ion channels in response to (ionic and non-ionic) hyperosmotic stresses and their interactions with signaling events leading to PCD in plant. Early cell responses such as cytosolic calcium increase and ROS production classically involved in PCD process, seems not to be involved in hyperosmotic-induced cell death in BY2 tobacco and A. thaliana cultured cells. When BY2 tobacco cells were subjected to hyperosmotic stress, an early influx of sodium through non-selective cation channels participates in the development of PCD through mitochondrial dysfunction and NADPH-oxidase-dependent O2•– generation. On the contrary, non-ionic hyperosmotic stress resulted in an early decrease in anion currents. To further investigate the role of anion channels in non-ionic hyperosmotic stress further experiments were conducted by using A.thaliana cells of the anion channel mutant SLAC1. Results showed that the delayed activation of SLAC1 channels was involved in the non-ionic hyperosmotic stress induced pathway leading to cell death. Interestingly, the early anion channel activity decrease could participate to signalisation or osmotic adjustment allowing cell adaptation and survival, when a second set of events, namely superoxide anion (O2•-) generation by NADPH-oxidase and anion channel activation could participate in PCD development of a part of the cell population. In addition, the potential role of small peptides belonging to the FMRFamide-like peptide (FLP) family described in metazoan in osmoregulation in A. thaliana was investigated. By using synthetic peptides, based on FLPs homolog genes existing in A. thaliana, it was possible to demonstrate that these putative FLPs are involved in hyperosmotic stress response. Overall, the present work shed light on the importance and the complexity of ion channels regulation in the signaling pathways and the processes leading to PCDLe travaux présenté dans cette thèse concerne le rôle des canaux ioniques de la membrane plasmique en réponse à des stress salins et non salins ainsi qu’aux interactions possibles avec d’autres événements de signalisation conduisant à la mort cellulaire programmée (PCD). Nous avons montré que les réponses cellulaires précoces: tels que l`augmentation du calcium cytosolique et la production de ROS, classiquement impliqués lors de la PCD, ne semblaient pas être impliqué dans la mort cellulaire induite par les stress hyperosmotiques chez les cellules en culture de tabacco BY2 ou d’A. thaliana. Nous avons montré que, dans les cas de stress salin chez les cellules de BY2 un influx précoce de sodium à travers des canaux cationiques non spécifiques participe au développement de la PCD en entraînant un disfonctionement mitochondrial et la production de O2• - par des NADPH oxydases. Dans le cas de stress hyperosmotique non-ionique, nous avons observé une diminaution précoce de l’intensité des courants anioniques. Afin de poursuivre l’étude du rôle des canaux anioniques lors du stress hyperosmotique non salin, nous avons utilisé des cellules A.thaliana nous permettant de travailler avec le mutant de canal anionique SLAC1. Nous avons constaté que l’activation retardée des canaux SLAC1 participait au développement de la PCD induite par un stress hyperosmotique non salin. La réduction précoce de l'activité des canaux anioniques pourrait participer à la signalisation ou l'ajustement osmotique permettant l'adaptation et la survie cellulaire alors que des évènements retardés, à savoir la production d'anion superoxyde (O2• -) par les NADPH-oxydases et l'activation des canaux anioniques pourraient participer au développement de la PCD d'une partie de la population cellulaire. Nous avons aussi étudié le rôle potentiel des petits peptides appartenant à la famille des peptides FMRFamide décrite chez les métazoaires à l'osmorégulation chez des cellules d’A. thaliana. Des génes susceptibles de coder de tels peptides sont en effet présent dans le génome d’A. thaliana. En utilisant des peptides synthétiques, nous avons montré que ces FLPS putatifs pourraient participer aux réponses induites losr de stress hyperosmotique chez les plantes. Ce travail illustre la complexité et l'importance de la régulation des canaux ioniques dans les voies de signalisation et les processus conduisant à la PC

Permutation complexity of interacting dynamical systems

The coupling complexity index is an information measure introduced within the framework of ordinal symbolic dynamics. This index is used to characterize the complexity of the relationship between dynamical system components. In this work, we clarify the meaning of the coupling complexity by discussing in detail some cases leading to extreme values, and present examples using synthetic data to describe its properties. We also generalize the coupling complexity index to the multivariate case and derive a number of important properties by exploiting the structure of the symmetric group. The applicability of this index to the multivariate case is demonstrated with a real-world data example. Finally, we define the coupling complexity rate of random and deterministic time series. Some formal results about the multivariate coupling complexity index have been collected in an Appendix.Comment: 16 pages, 6 figure

The RIB production target for the SPES project

Facilities making use of the Isotope Separator On-Line (ISOL) method for the production of Radioactive Ion Beams (RIB) attract interest because they can be used for nuclear structure and reaction studies, astrophysics research and interdisciplinary applications. The ISOL technique is based on the fast release of the nuclear reaction products from the chosen target material together with their ionization into short-lived nuclei beams. Within this context, the SPES (Selective Production of Exotic Species) facility is now under construction in Italy at INFN-LNL (Istituto Nazionale di Fisica Nucleare — Laboratori Nazionali di Legnaro). The SPES facility will produce RIBs mainly from n-rich isotopes obtained by a 40 MeV cyclotron proton beam (200 μA) directly impinging on a uranium carbide multi-foil fission target. The aim of this work is to describe and update, from a comprehensive point of view, the most important results obtained by the analysis of the on-line behavior of the SPES production target assembly. In particular an improved target configuration has been studied by comparing different codes and physics models: the thermal analyses and the isotope production are re-evaluated. Then some consequent radioprotection aspects, which are essential for the installation and operation of the facility, are presented