High-order harmonic generation in a driven two-level atom: Periodic level crossings and three-step processes

We investigate high-order harmonic generation in closed systems using the two-level atom as a simplified model. By means of a windowed Fourier transform of the time-dependent dipole acceleration, we extract the main contributions to this process within a cycle of the driving field. We show that the patterns obtained can be understood by establishing a parallel between the two-level atom and the three-step model. In both models, high-order harmonic generation is a consequence of a three-step process, which involves either the continuum and the ground state, or the adiabatic states of the two-level Hamiltonian. The knowledge of this physical mechanism allows us to manipulate the adiabatic states, and consequently the harmonic spectra, by means of a bichromatic driving field. Furthermore, using scaling laws, we establish sharp criteria for the invariance of the physical quantities involved. Consequently, our results can be extended to a broader parameter range, as, for instance, those characteristic of solid-state systems in strong fields

Atomic Focusing by Quantum Fields: Entanglement Properties

The coherent manipulation of the atomic matter waves is of great interest both in science and technology. In order to study how an atom optic device alters the coherence of an atomic beam, we consider the quantum lens proposed by Averbukh et al [1] to show the discrete nature of the electromagnetic field. We extend the analysis of this quantum lens to the study of another essentially quantum property present in the focusing process, i.e., the atom-field entanglement, and show how the initial atomic coherence and purity are affected by the entanglement. The dynamics of this process is obtained in closed form. We calculate the beam quality factor and the trace of the square of the reduced density matrix as a function of the average photon number in order to analyze the coherence and purity of the atomic beam during the focusing process.Comment: 10 pages, 4 figure

Vacuumless kinks systems from vacuum ones, an example

Some years ago, Cho and Vilenkin, introduced a model which presents topological solutions, despite not having degenerate vacua as is usually expected. Here we present a new model with topological defects, connecting degenerate vacua but which in a certain limit recovers precisely the one proposed originally by Cho and Vilenkin. In other words, we found a kind of parent model for the so called vacuumless model. Then the idea is extended to a model recently introduced by Bazeia et al. Finally, we trace some comments the case of the Liouville model.Comment: 11 pages, 4 figure

Runoff at the micro-plot and slope scale following wildfire, central Portugal

Through their effects on soil properties and vegetation/litter cover, wildfires can strongly enhance overland flow generation and accelerate soil erosion [1] and, thereby, negatively affect land-use sustainability as well as downstream aquatic and flood zones. Wildfires are a common phenomenon in present-day Portugal, devastating in an average year some 100.000 ha of forest and woodlands and in an exceptional year like 2003 over 400.000 ha. There therefore exists a clear need in Portugal for a tool that can provide guidance to post-fire land management by predicting soil erosion risk, on the one hand, and, on the other, the mitigation effectiveness of soil conservation measures. Such a tool has recently been developed for the Western U.S.A. [3: ERMiT] but its suitability for Portuguese forests will need to be corroborated by field observations. Testing the suitability of existing erosion models in recently burned forest areas in Portugal is, in a nutshell, the aim of the EROSFIRE projects. In the first EROSFIRE project the emphasis was on the prediction of erosion at the scale of individual hill slopes. In the ongoing EROSFIRE-II project the spatial scope is extended to include the catchment scale, so that also the connectivity between hill slopes as well as channel and road processes are being addressed. Besides ERMiT, the principal models under evaluation for slope-scale erosion prediction are: (i) the variant of USLE [4] applied by the Portuguese Water Institute after the wildfires of 2003; (ii) the Morgan–Morgan–Finney model (MMF) [5]; (iii) MEFIDIS [6]. From these models, MEFIDIS and perhaps MMF will, after successful calibration at the slope scale, also be applied for predicting catchment-scale sediment yields of extreme events

Personalizing paper-and-pencil training for cognitive rehabilitation: a feasibility study with a web-based Task Generator

Cognitive impairments impose important limitations in the performance of activities of daily living. Although there is important evidence on cognitive rehabilitation benefits, its implementation is limited due to the demands in terms of time and human resources. Moreover, many cognitive rehabilitation interventions lack a solid theoretical framework in the selection of paper-and-pencil tasks by the clinicians. In this endeavor, it would be useful to have a tool that could generate standardized paper-and pencil tasks, customized according to patients’ needs. Combining the advantages of information and communication technologies (ICT’s) with a participatory design approach involving 20 health professionals, a novel web-tool for the generation of cognitive rehabilitation training was developed: the Task Generator (TG). The TG is a web-based tool that systematically addresses multiple cognitive domains, and easily generates highly personalized paper and-pencil training tasks. A clinical evaluation of the TG with twenty stroke patients showed that, by enabling the adaptation of task parameters and difficulty levels according to patient cognitive assessment, this tool provides a comprehensive cognitive training.info:eu-repo/semantics/publishedVersio

Runoff and erosion at the micro-plot and slope scale in a small burnt catchment, central Portugal

Wildfires can have important impacts on hydrological processes and soil erosion in forest catchments, due to the destruction of vegetation cover and changes to soil properties. However, the processes involved are non-linear and not fully understood. This has severely limited the understanding on the impacts of wildfires, especially in the up-scaling from hillslopes to catchments; in consequence, current models are poorly adapted for burnt forest conditions. The objective of this presentation is to give an overview of the hydrological response and sediment yield from the micro-plot to slope scale, in the first year following a wildfire (2008/2009) that burnt an entire catchment nearby the Colmeal village, central Portugal. The overview will focus on three slopes inside the catchment, with samples including: • Runoff at micro-plot scale (12 bounded plots) and slope scale (12 open plots); • Sediments and Organic Matter loss at micro-plot scale (12 bounded plots) and slope scale (12 open plots plus 3 Sediment fences); • Rainfall and Soil moisture data; • Soil Water Repellency and Ground Cover data. The analysis of the first year following the wildfire clearly shows the complexity of runoff generation and the associated sediment transport in recently burnt areas, with pronounced differences between hillslopes and across spatial scales as well as with marked variations through time. This work was performed in the framework of the EROSFIRE-II project (PTDC/AGR-CFL/70968/2006) which has as overall aim to predict soil erosion risk in recently burnt forest areas, including common post-fire forest management practices; the project focuses on the simultaneous measurement of runoff and soil erosion at multiple spatial scales.The results to be presented in this session are expected to show how sediment is generated, transported and exported in the Colmeal watershed; and contribute to understand and simulate erosion processes in burnt catchments, including for model development and evaluation

Enhancing the production of mannosylglycerate in s. cerevisiae through in silico driven metabolic engineering

Mannosylglycerate (MG) is a compatible solute with major potential applications in the cosmetic industry, as moisturizer and skin protector against UV damage, storage of vaccines and other biomaterials, or protein stabilizer in analytical and clinical kits. Since the production of MG is expensive the development of efficient production systems is mandatory to fully exploit the potential of this solute. Saccharomyces cerevisiae was selected to produce MG, which is synthesized by the condensation of GDP-mannose and 3-phosphoglycerate. To better understand the impact of this pathway in yeast metabolism, the two enzymatic reactions were accommodated and evaluated in silico using the yeast genome scale metabolic model IMM904. Several optimization algorithms were ran to find the sets of genetic modification that lead to maximization of MG production. Results show that the production can be optimized by increasing the flow towards GDP-mannose formation and by introducing a bottleneck in the synthesis of pyruvate. This metabolic engineering strategy that targets the increased supply of biosynthetic precursors was implemented in vivo. Results show that MG accumulation increases 1.5-fold by overexpressing the genes involved in formation of GDP-mannose. However, no effect in the production of MG was observed when 3-phosphoglycerate was overproduced. Moreover, higher yields of MG were obtained when the mutants were cultivated in chemostast in comparison with batch mode

Internova e-learning platform in an entrepreneurial context

Currently, there is still an opposition of teachers to the implementation of new technologies in an educational context. Although several studies point out the relevance of the use of information and communication technologies in pedagogical practices, providing educational contexts more focused on learning practices and fostering more active and autonomous professionals. In this context, this article emphasizes the purpose of using Information and Communication Technologies (ICT), as well as virtual learning environments, in the higher education system, to support the teaching-learning processes. In this article, a state of the art was carried out, in order to demonstrate some advantages of the teaching-learning process, the teacher's and student behaviour profiles and its role in relation to the use of new technologies. The objective of this study was to analyse the impact of using a digital platform on the teaching-learning process in an educational context. An e-learning digital platform, INTERNOVA, developed within the scope of the INTERNOVAMARKET-FOOD project (0437_internovamarket-food_1_E - Internovamarket accelerator program to increase the competitiveness of the food sector in Galicia-Northern), within the curricular unit of Food Safety and Certification of the Master in Food Engineering's curriculum. In order to assess the impact of the training course on the students' learning outcomes, a survey was applied to master's students and Food Engineering research fellows (participants). The same survey was applied before the training and after it in order to compare both results. At the end of each training course, another survey was addressed to all the participants asking about the organization, quality and the easiness of the platform. The results obtained show that the students had no difficulties in using the platform, having revealed that they would like to continue using it more frequently. The data obtained are an evidence of the participants' learning improvement and their involvement in the learning process through the INTERNOVA platform. With this work, it can be concluded that the ICT applied to a curricular program can be a very important support in the teaching-learning process. In this context, it is important to recommend well-designed curricular programs so that teachers can improve their teaching practices, enhancing students' digital skills, and thus contributing to the development of more active and autonomous professionals. © Proceedings of the 14th IADIS International Conference e-Learning 2020, EL 2020 - Part of the 14th Multi Conference on Computer Science and Information Systems, MCCSIS 2020. All rights reserved.This work was supported by INTERREG V-A Espanha-Portugal (POCTEP) 2014-2020 (0437_INTERNOVAMARKET-FOOD_1_E) under the development of the project entitled “INTERNOVAMARKET-FOOD – Programa acelerador para aumentar a competitividade do sector alimentar da Galiza-Norte de Portugal”info:eu-repo/semantics/publishedVersio