Quasi-static Limits in Nonrelativistic Quantum Electrodynamics

We consider a system of N nonrelativistic particles of spin 1/2 interacting with the quantized Maxwell field (mass zero and spin one) in the limit when the particles have a small velocity, imposing to the interaction an ultraviolet cutoff, but no infrared cutoff. Two ways to implement the limit are considered: c going to infinity with the velocity v of the particles fixed, the case for which rigorous results have already been discussed in the literature, and v going to 0 with c fixed. The second case can be rephrased as the limit of heavy particles, m_{j} --> epsilon^{-2}m_{j}, observed over a long time, t --> epsilon^{-1}t, epsilon --> 0^{+}, with kinetic energy E_{kin} = Or(1). Focusing on the second approach we construct subspaces which are invariant for the dynamics up to terms of order epsilon sqrt{log(epsilon^{-1})} and describe effective dynamics, for the particles only, inside them. At the lowest order the particles interact through Coulomb potentials. At the second one, epsilon^{2}, the mass gets a correction of electromagnetic origin and a velocity dependent interaction, the Darwin term, appears. Moreover, we calculate the radiated piece of the wave function, i. e., the piece which leaks out of the almost invariant subspaces and calculate the corresponding radiated energy.Comment: 46 pages, no figures. Minor changes in the introduction and correction of some typos. Version accepted for publication in Annales Henri Poincare

Evidence-based recommendation on toothpaste use

Toothpaste can be used as a vehicle for substances to improve the oral health of individuals and populations. Therefore, it should be recommended based on the best scientific evidence available, and not on the opinion of authorities or specialists. Fluoride is the most important therapeutic substance used in toothpastes, adding to the effect of mechanical toothbrushing on dental caries control. The use of fluoride toothpaste to reduce caries in children and adults is strongly based on evidence, and is dependent on the concentration (minimum of 1000 ppm F) and frequency of fluoride toothpaste use (2×/day or higher). The risk of dental fluorosis due to toothpaste ingestion by children has been overestimated, since there is no evidence that: 1) fluoride toothpaste use should be postponed until the age of 3-4 or older, 2) low-fluoride toothpaste avoids fluorosis and 3) fluorosis has a detrimental effect on the quality of life of individuals exposed to fluoridated water and toothpaste. Among other therapeutic substances used in toothpastes, there is evidence that triclosan/copolymer reduce dental biofilm, gingivitis, periodontitis, calculus and halitosis, and that toothpastes containing stannous fluoride reduce biofilm and gingivitis.Toothpaste can be used as a vehicle for substances to improve the oral health of individuals and populations. Therefore, it should be recommended based on the best scientific evidence available, and not on the opinion of authorities or specialists. Fluoride is the most important therapeutic substance used in toothpastes, adding to the effect of mechanical toothbrushing on dental caries control. The use of fluoride toothpaste to reduce caries in children and adults is strongly based on evidence, and is dependent on the concentration (minimum of 1000 ppm F) and frequency of fluoride toothpaste use (2×/day or higher). The risk of dental fluorosis due to toothpaste ingestion by children has been overestimated, since there is no evidence that: 1) fluoride toothpaste use should be postponed until the age of 3-4 or older, 2) low-fluoride toothpaste avoids fluorosis and 3) fluorosis has a detrimental effect on the quality of life of individuals exposed to fluoridated water and toothpaste. Among other therapeutic substances used in toothpastes, there is evidence that triclosan/copolymer reduce dental biofilm, gingivitis, periodontitis, calculus and halitosis, and that toothpastes containing stannous fluoride reduce biofilm and gingivitis28111

A Jewelry-Tech Experience: Teaching and Learning Model for Academic Training

[EN] The paper aims to describe an innovative teaching and learning process in jewelry-tech design. First of all, the paper analyzes the contemporary and multidisciplinary context, underlining the growing presence of a close connection between digital technologies and the world of accessory design, particularly jewelry. The need to define learning models that aim to integrate different skills to train new professional figures successfully is outlined in this context. Secondly, the paper presents and examines the case study "name of the workshop" held at the "name of the university," an international workshop conducted in academic training in collaboration with an Italian jewelry company. The results obtained during this experience are presented and underline effective methodologies and critical issues in conducting the workshop.Tenuta, L.; Cappellieri, A.; Testa, S.; Rossato, B. (2022). A Jewelry-Tech Experience: Teaching and Learning Model for Academic Training. En 8th International Conference on Higher Education Advances (HEAd'22). Editorial Universitat Politècnica de València. 609-618. https://doi.org/10.4995/HEAd22.2022.1461760961

Quantum graphs as holonomic constraints

We consider the dynamics on a quantum graph as the limit of the dynamics generated by a one-particle Hamiltonian in R^2 with a potential having a deep strict minimum on the graph, when the width of the well shrinks to zero. For a generic graph we prove convergence outside the vertices to the free dynamics on the edges. For a simple model of a graph with two edges and one vertex, we prove convergence of the dynamics to the one generated by the Laplacian with Dirichlet boundary conditions in the vertex.Comment: 28 pages, 3 figure

Fluoride concentration in the top-selling brazilian toothpastes purchased at different regions

To be relevant in terms of public health, widely-used toothpastes should have at least 1,000 ppm of soluble fluoride (F) concentration. Thus, the concentrations of total fluoride (TF) and total soluble fluoride (TSF) in the top-selling Brazilian toothpastes were evaluated. Samples (n=3) from toothpastes Colgate Anti-cáries®, Colgate Total 12 Clean Mint®, Colgate Tripla Ação Menta Original®, Colgate Tripla Ação Menta Suave® and Sorriso Dentes Brancos® were obtained from each of the five regions of the country. The concentrations of TF and TSF were analyzed with ion-specific electrode calibrated with F standards and the results were expressed in ppm (μg F/g). All toothpastes showed TF concentration lower than 1,500 ppm F (1,388.2 ± 25.8 to 1,483.2 ± 98.2). The TSF values were higher than 1,000 ppm F and ranged from 1,035.5 ± 61.5 to 1,221.8 ± 35.2 for calcium carbonate/monofluorophosphate-based toothpastes and from 1,455.6 ± 12.5 to 1,543.0 ± 147.3 for silica/sodium fluoride-based toothpaste. Top-selling Brazilian toothpastes presented available fluoride concentration to control caries regardless of the region where they are purchased.To be relevant in terms of public health, widely-used toothpastes should have at least 1,000 ppm of soluble fluoride (F) concentration. Thus, the concentrations of total fluoride (TF) and total soluble fluoride (TSF) in the top-selling Brazilian toothpastes were evaluated. Samples (n=3) from toothpastes Colgate Anti-cáries®, Colgate Total 12 Clean Mint®, Colgate Tripla Ação Menta Original®, Colgate Tripla Ação Menta Suave® and Sorriso Dentes Brancos® were obtained from each of the five regions of the country. The concentrations of TF and TSF were analyzed with ion-specific electrode calibrated with F standards and the results were expressed in ppm (μg F/g). All toothpastes showed TF concentration lower than 1,500 ppm F (1,388.2 ± 25.8 to 1,483.2 ± 98.2). The TSF values were higher than 1,000 ppm F and ranged from 1,035.5 ± 61.5 to 1,221.8 ± 35.2 for calcium carbonate/monofluorophosphate-based toothpastes and from 1,455.6 ± 12.5 to 1,543.0 ± 147.3 for silica/sodium fluoride-based toothpaste. Top-selling Brazilian toothpastes presented available fluoride concentration to control caries regardless of the region where they are purchased2314548Para ter relevância em termos de saúde pública, os cremes dentais amplamente utilizados pela população devem ter fluoreto (F) solúvel numa concentração mínima de 1.000 ppm F. Assim, as concentrações de fluoreto total (FT) e flureto solúvel total (FST) nos cremes dentais mais vendidos no Brasil foram avaliados. Os cremes dentais (n=3) Colgate Anti-cáries®, Colgate Total 12 Clean Mint®, Colgate Tripla Ação Menta Original®, Colgate Tripla Ação Menta Suave® e Sorriso Dentes Brancos® foram obtidos nas cinco regiões do país. As concentrações de FT e FST foram analisadas com eletrodo íon-específico calibrado com padrões de F e os resultados foram expressos em ppm (µg F/g). Todos os cremes dentais apresentaram concentração de FT inferior a 1.500 ppm F (1.388,2 ± 25,8 a 1.483,2 ± 98,2). Os valores de FST foram superiores a 1.000 ppm F e variaram de 1.035,5 ± 61,5 a 1.221,8 ± 35,2 para cremes dentais a base de carbonato de cálcio/monofluorfosfato e de 1.455,6 ± 12,5 a 1.543,0 ± 147,3 para o creme dental à base de sílica/fluoreto de sódio. Os cremes dentais mais vendidos no Brasil apresentaram concentração de fluoreto solúvel para controlar cárie, independentemente da região onde foram comprado

Development of Crop.LCA, an adaptable screening life cycle assessment tool for agricultural systems: a Canadian scenario assessment

There is an increasing demand for sustainable agricultural production as part of the transition towards a globally sustainable economy. To quantify impacts of agricultural systems on the environment, life cycle assessment (LCA) is ideal because of its holistic approach. Many tools have been developed to conduct LCAs in agriculture, but they are not publicly available, not open-source, and have a limited scope. Here, a new adaptable open-source tool (Crop.LCA) for carrying out LCA of cropping systems is presented and tested in an evaluation study with a scenario assessment of 4 cropping systems using an agroecosystem model (DNDC) to predict soil GHG emissions. The functional units used are hectares (ha) of land and gigajoules (GJ) of harvested energy output, and 4 impact categories were evaluated: cumulative energy demand (CED), 100-year global warming potential (GWP), eutrophication and acidification potential. DNDC was used to simulate 28 years of cropping system dynamics, and the results were used as input in Crop.LCA. Data were aggregated for each 4-year rotation and statistically analyzed. Introduction of legumes into the cropping system reduced CED by 6%, GWP by 23%, and acidification by 19% per ha. These results highlight the ability of Crop.LCA to capture cropping system characteristics in LCA, and the tool constitutes a step forward in increasing the accuracy of LCA of cropping systems as required for bio-economy system assessments. Furthermore, the tool is open-source, highly transparent and has the necessary flexibility to assess agricultural systems

Development of Crop.LCA, an adaptable screening life cycle assessment tool for agricultural systems: a Canadian scenario assessment

There is an increasing demand for sustainable agricultural production as part of the transition towards a globally sustainable economy. To quantify impacts of agricultural systems on the environment, life cycle assessment (LCA) is ideal because of its holistic approach. Many tools have been developed to conduct LCAs in agriculture, but they are not publicly available, not open-source, and have a limited scope. Here, a new adaptable open-source tool (Crop.LCA) for carrying out LCA of cropping systems is presented and tested in an evaluation study with a scenario assessment of 4 cropping systems using an agroecosystem model (DNDC) to predict soil GHG emissions. The functional units used are hectares (ha) of land and gigajoules (GJ) of harvested energy output, and 4 impact categories were evaluated: cumulative energy demand (CED), 100-year global warming potential (GWP), eutrophication and acidification potential. DNDC was used to simulate 28 years of cropping system dynamics, and the results were used as input in Crop.LCA. Data were aggregated for each 4-year rotation and statistically analyzed. Introduction of legumes into the cropping system reduced CED by 6%, GWP by 23%, and acidification by 19% per ha. These results highlight the ability of Crop.LCA to capture cropping system characteristics in LCA, and the tool constitutes a step forward in increasing the accuracy of LCA of cropping systems as required for bio-economy system assessments. Furthermore, the tool is open-source, highly transparent and has the necessary flexibility to assess agricultural systems