Global well-posedness of the KP-I initial-value problem in the energy space

We prove that the KP-I initial value problem is globally well-posed in the natural energy space of the equation

Adaptive Mesh Refinement for Characteristic Grids

I consider techniques for Berger-Oliger adaptive mesh refinement (AMR) when numerically solving partial differential equations with wave-like solutions, using characteristic (double-null) grids. Such AMR algorithms are naturally recursive, and the best-known past Berger-Oliger characteristic AMR algorithm, that of Pretorius & Lehner (J. Comp. Phys. 198 (2004), 10), recurses on individual "diamond" characteristic grid cells. This leads to the use of fine-grained memory management, with individual grid cells kept in 2-dimensional linked lists at each refinement level. This complicates the implementation and adds overhead in both space and time. Here I describe a Berger-Oliger characteristic AMR algorithm which instead recurses on null \emph{slices}. This algorithm is very similar to the usual Cauchy Berger-Oliger algorithm, and uses relatively coarse-grained memory management, allowing entire null slices to be stored in contiguous arrays in memory. The algorithm is very efficient in both space and time. I describe discretizations yielding both 2nd and 4th order global accuracy. My code implementing the algorithm described here is included in the electronic supplementary materials accompanying this paper, and is freely available to other researchers under the terms of the GNU general public license.Comment: 37 pages, 15 figures (40 eps figure files, 8 of them color; all are viewable ok in black-and-white), 1 mpeg movie, uses Springer-Verlag svjour3 document class, includes C++ source code. Changes from v1: revised in response to referee comments: many references added, new figure added to better explain the algorithm, other small changes, C++ code updated to latest versio

Categorizing Different Approaches to the Cosmological Constant Problem

We have found that proposals addressing the old cosmological constant problem come in various categories. The aim of this paper is to identify as many different, credible mechanisms as possible and to provide them with a code for future reference. We find that they all can be classified into five different schemes of which we indicate the advantages and drawbacks. Besides, we add a new approach based on a symmetry principle mapping real to imaginary spacetime.Comment: updated version, accepted for publicatio

Mudança de paradigma no ensino da Bioquímica na licenciatura em Ciências da Nutrição na Universidade do Porto

No primeiro ano da licenciatura em Ciências da Nutrição, na Faculdade de Ciências da Nutriçãoe Alimentação, da Universidade do Porto, existem duas Unidades Curriculares que introduzem aBioquímica aos estudantes [Química Orgânica e Bioquímica I (no 1º e 2º semestres,respetivamente)] e cujos programas e modalidades pedagógicas estão inter-relacionados,confrontando o estudante, progressivamente ao longo do ano letivo, com oportunidades deaprendizagem ativa.A divulgação de descobertas científicas e o envolvimento dos estudantes em projetos deinvestigação científica melhoram a aprendizagem e a retenção de conhecimentos, assim comooperacionalizam a sua aplicabilidade prática, ao mesmo tempo que desenvolvem um efeitopositivo no interesse pela investigação científica.Com o objetivo de melhorar não só a aquisição de conhecimentos, mas também a compreensão e aplicabilidade dos mesmos, assim como o desenvolvimento de competências e de raciocíniohipotético-dedutivo pelos estudantes, o ensino da Bioquímica "tradicional/clássico/base" foimodificado de modo a: 1) introduzir a discussão de artigos científicos relevantes (nas sessõesteóricas e/ou práticas); 2) possibilitar o contacto com a investigação científica feita pelosdocentes (nas sessões teóricas) e 3) possibilitar a realização de pequenos projetos deinvestigação científica (nas sessões práticas). Nestas 3 modalidades pedagógicas estãosubjacentes temas bioquímicos que integram o programa "clássico/base" das referidas UnidadesCurriculares. Adicionalmente, ao estudante são divulgados, nas 3 modalidades pedagógicasacima referidas, temas atuais da Bioquímica Nutricional ao mesmo tempo que contacta comtodas as fases da metodologia de aquisição de conhecimentos, de raciocínio e de investigaçãousadas na área da Nutrição

A scoping review establishes need for consensus guidance on reporting health equity in observational studies.

To evaluate the support from the available guidance on reporting of health equity in research for our candidate items and to identify additional items for the Strengthening Reporting of Observational studies in Epidemiology-Equity extension. We conducted a scoping review by searching Embase, MEDLINE, CINAHL, Cochrane Methodology Register, LILACS, and Caribbean Center on Health Sciences Information up to January 2022. We also searched reference lists and gray literature for additional resources. We included guidance and assessments (hereafter termed "resources") related to conduct and/or reporting for any type of health research with or about people experiencing health inequity. We included 34 resources, which supported one or more candidate items or contributed to new items about health equity reporting in observational research. Each candidate item was supported by a median of six (range: 1-15) resources. In addition, 12 resources suggested 13 new items, such as "report the background of investigators". Existing resources for reporting health equity in observational studies aligned with our interim checklist of candidate items. We also identified additional items that will be considered in the development of a consensus-based and evidence-based guideline for reporting health equity in observational studies

ECOS-LINCE:A high-intensity heavy-ion facility for nuclear structure and reactions

During the last years, the ECOS working group has been considering the construction of a new high-intensity accelerator of stable ion beams for the next Long-Range Plan of the nuclear physics community in Europe. The new facility (LINCE) will be a multi-user facility dedicated to ECOS science: fundamental physics, astrophysics, nuclear structure and reaction dynamics. In this paper, we summarize preliminary design studies of the low-energy part of this facility based on the use of a multi-ion superconducting linac. [ABSTRACT FROM AUTHOR

Performance of novel VUV-sensitive Silicon Photo-Multipliers for nEXO

Liquid xenon time projection chambers are promising detectors to search for neutrinoless double beta decay (0$\nu \beta \beta$), due to their response uniformity, monolithic sensitive volume, scalability to large target masses, and suitability for extremely low background operations. The nEXO collaboration has designed a tonne-scale time projection chamber that aims to search for 0$\nu \beta \beta$ of \ce{^{136}Xe} with projected half-life sensitivity of $1.35\times 10^{28}$~yr. To reach this sensitivity, the design goal for nEXO is $\leq$1\% energy resolution at the decay $Q$-value ($2458.07\pm 0.31$~keV). Reaching this resolution requires the efficient collection of both the ionization and scintillation produced in the detector. The nEXO design employs Silicon Photo-Multipliers (SiPMs) to detect the vacuum ultra-violet, 175 nm scintillation light of liquid xenon. This paper reports on the characterization of the newest vacuum ultra-violet sensitive Fondazione Bruno Kessler VUVHD3 SiPMs specifically designed for nEXO, as well as new measurements on new test samples of previously characterised Hamamatsu VUV4 Multi Pixel Photon Counters (MPPCs). Various SiPM and MPPC parameters, such as dark noise, gain, direct crosstalk, correlated avalanches and photon detection efficiency were measured as a function of the applied over voltage and wavelength at liquid xenon temperature (163~K). The results from this study are used to provide updated estimates of the achievable energy resolution at the decay $Q$-value for the nEXO design