Properties of nuclei up to A=16A=16 using local chiral interactions

We report accurate quantum Monte Carlo calculations of nuclei up to $A=16$ based on local chiral two- and three-nucleon interactions up to next-to-next-to-leading order. We examine the theoretical uncertainties associated with the chiral expansion and the cutoff in the theory, as well as the associated operator choices in the three-nucleon interactions. While in light nuclei the cutoff variation and systematic uncertainties are rather small, in $^{16}$O these can be significant for large coordinate-space cutoffs. Overall, we show that chiral interactions constructed to reproduce properties of very light systems and nucleon-nucleon scattering give an excellent description of binding energies, charge radii, and form factors for all these nuclei, including open-shell systems in $A=6$ and 12.Comment: 6 pages, 4 figure

Auxiliary field diffusion Monte Carlo calculations of light and medium-mass nuclei with local chiral interactions

Quantum Monte Carlo methods have recently been employed to study properties of nuclei and infinite matter using local chiral effective field theory interactions. In this work, we present a detailed description of the auxiliary field diffusion Monte Carlo algorithm for nuclei in combination with local chiral two- and three-nucleon interactions up to next-to-next-to-leading order. We show results for the binding energy, charge radius, charge form factor, and Coulomb sum rule in nuclei with $3\le A\le16$. Particular attention is devoted to the effect of different operator structures in the three-body force for different cutoffs. The outcomes suggest that local chiral interactions fit to few-body observables give a very good description of the ground-state properties of nuclei up to $^{16}$O, with the exception of one fit for the softer cutoff which predicts overbinding in larger nuclei.Comment: 23 pages, 10 figure

High-resolution bioelectrical imaging of Aβ-induced network dysfunction on CMOS-MEAs for neurotoxicity and rescue studies

Neurotoxicity and the accumulation of extracellular amyloid-beta1-42 (A\u3b2) peptides are associated with the development of Alzheimer's disease (AD) and correlate with neuronal activity and network dysfunctions, ultimately leading to cellular death. However, research on neurodegenerative diseases is hampered by the paucity of reliable readouts and experimental models to study such functional decline from an early onset and to test rescue strategies within networks at cellular resolution. To overcome this important obstacle, we demonstrate a simple yet powerful in vitro AD model based on a rat hippocampal cell culture system that exploits large-scale neuronal recordings from 4096-electrodes on CMOS-chips for electrophysiological quantifications. This model allows us to monitor network activity changes at the cellular level and to uniquely uncover the early activity-dependent deterioration induced by A\u3b2-neurotoxicity. We also demonstrate the potential of this in vitro model to test a plausible hypothesis underlying the A\u3b2-neurotoxicity and to assay potential therapeutic approaches. Specifically, by quantifying N-methyl D-aspartate (NMDA) concentration-dependent effects in comparison with low-concentration allogenic-A\u3b2, we confirm the role of extrasynaptic-NMDA receptors activation that may contribute to A\u3b2-neurotoxicity. Finally, we assess the potential rescue of neural stem cells (NSCs) and of two pharmacotherapies, memantine and saffron, for reversing A\u3b2-neurotoxicity and rescuing network-wide firing

Recent progress on the accurate determination of the equation of state of neutron and nuclear matter

The problem of accurately determining the equation of state of nuclear and neutron matter at density near and beyond saturation is still an open challenge. In this paper we will review the most recent progress made by means of Quantum Monte Carlo calculations, which are at present the only ab-inito method capable to treat a sufficiently large number of particles to give meaningful estimates depending only on the choice of the nucleon-nucleon interaction. In particular, we will discuss the introduction of density-dependent interactions, the study of the temperature dependence of the equation of state, and the possibility of accurately studying the effect of the onset of hyperons by developing an accurate hyperon-nucleon and hyperon-nucleon-nucleon interaction.Comment: 3 figures, 1 table, to appear in the Proceedings of "XIII Convegno di Cortona su Problemi di Fisica Nucleare Teorica", Cortona (Italy), April 6-8, 201

Comparing proton momentum distributions in A=2A=2 and 3 nuclei via 2^2H 3^3H and 3^3He (e,e′p)(e, e'p) measurements

We report the first measurement of the $(e,e'p)$ reaction cross-section ratios for Helium-3 ($^3$He), Tritium ($^3$H), and Deuterium ($d$). The measurement covered a missing momentum range of $40 \le p_{miss} \le 550$ MeV$/c$, at large momentum transfer ($\langle Q^2 \rangle \approx 1.9$ (GeV$/c$)$^2$) and $x_B>1$, which minimized contributions from non quasi-elastic (QE) reaction mechanisms. The data is compared with plane-wave impulse approximation (PWIA) calculations using realistic spectral functions and momentum distributions. The measured and PWIA-calculated cross-section ratios for $^3$He$/d$ and $^3$H$/d$ extend to just above the typical nucleon Fermi-momentum ($k_F \approx 250$ MeV$/c$) and differ from each other by $\sim 20\%$, while for $^3$He/$^3$H they agree within the measurement accuracy of about 3\%. At momenta above $k_F$, the measured $^3$He/$^3$H ratios differ from the calculation by $20\% - 50\%$. Final state interaction (FSI) calculations using the generalized Eikonal Approximation indicate that FSI should change the $^3$He/$^3$H cross-section ratio for this measurement by less than 5\%. If these calculations are correct, then the differences at large missing momenta between the $^3$He/$^3$H experimental and calculated ratios could be due to the underlying $NN$ interaction, and thus could provide new constraints on the previously loosely-constrained short-distance parts of the $NN$ interaction.Comment: 8 pages, 3 figures (4 panels

Estágio curricular no gabinete de engenharia ACet, na componente de climatização

Trabalho final de mestrado para obtenção do grau de mestre em Engenharia Mecânica com especialização em Energia, Climatização e RefrigeraçãoÉ âmbito do presente documento descrever as actividades desenvolvidas durante o estágio curricular na empresa ACet, ANTERO CARDOSO - Engenharia Termodinâmica, Lda. O mesmo constitui-se como documento final de curso, do Mestrado em Engenharia Mecânica, ramo de Energia, Refrigeração e Climatização, do Instituto Superior de Engenharia de Lisboa. A empresa ACet, ANTERO CARDOSO - Engenharia Termodinâmica, Lda tem como actividade a elaboração de estudos e projectos de engenharia e consultoria de instalações especiais. Adicionalmente, a empresa inclui serviços de preparação, coordenação e fiscalização de obras. Na elaboração do relatório de estágio foram efectuadas diversas pesquisas de carácter informativo, bem como consultas às diversas normas e legislações em vigor, que permitiram desenvolver e adquirir conhecimentos relacionados com execução de um projecto. Desta forma, salienta-se que o presente relatório tem como intuito não só descrever as actividades desenvolvidas ao longo do estágio, como também apresentar um breve enquadramento teórico do conhecimento adquirido durante a realização do mesmo, bem como ao longo do percurso académico. O presente trabalho é essencialmente dividido em três partes, sendo que na primeira parte será efectuada uma abordagem a todos os parâmetros e requisitos necessários para a actividade da ACet, visando o cumprimento das normas vigentes, no que diz respeito ao conforto térmico, ventilação e qualidade do ar interior. Numa segunda fase, serão abordados os diferentes sistemas de AVAC existentes, bem como o dimensionamento dos diversos equipamentos e das respectivas redes hidráulicas e aeráulicas. Por fim, na terceira parte do relatório serão descritos os projectos acompanhados e desenvolvidos ao longo do estágio curricular, bem como as conclusões finais retiradas de todo o trabalho efectuado. As três partes descritas são constituídas por diversos capítulos. Na primeira parte estão incluídos os capítulos 1, 2, 3, 4 e 5, na segunda parte os capítulos 6, 7, 8 e 9 e por fim na terceira parte os capítulos 10, 11 e 12.Abstract: The scope of this thesis is to describe the activities developed during the internship at ACet, ANTERO CARDOSO – Thermodynamics Engineering, Ltd. This is a final work Master degree in Mechanical Engineering, in the area of Energy, Refrigeration and Air Conditioning, of ISEL Polytechnic Institute. The main activity of ACet, ANTERO CARDOSO – Thermodynamics Engineering, Ltd is the conception of studies and engineering designs and consulting for special installations. Additionally, the company includes services of preparation, coordination and supervision of works. During the preparation of this report several surveys were made, as well as consultations to the current laws, which have allowed to develop and acquire knowledge about project development. Thus, the present report has the purpose not only to describe the activities developed, but also to introduce a theoretical framework about the knowledge acquired during the internship, as well as during the academic path. This report is divided essentially in three parts. In the first part, an approach will be made to all parameters and necessary requirements, in order to comply with current regulations, regarding the thermal comfort, ventilation and indoor air quality. The second part will include a description of different types of HVAC systems and explains the dimensioning principles about the equipment and the network distribution of fluids like air and water. The last part of the report will present the description of all the projects that were subject to study during the internship followed by the conclusions about all the work done. The three parts are composed by several chapters. In the first part chapters 1, 2, 3, 4 and 5 are included. The second part contains the chapters 6, 7, 8 and 9 while the third and final part includes the chapters 10, 11 and 12.N/