Continuum variational and diffusion quantum Monte Carlo calculations

This topical review describes the methodology of continuum variational and diffusion quantum Monte Carlo calculations. These stochastic methods are based on many-body wave functions and are capable of achieving very high accuracy. The algorithms are intrinsically parallel and well-suited to petascale computers, and the computational cost scales as a polynomial of the number of particles. A guide to the systems and topics which have been investigated using these methods is given. The bulk of the article is devoted to an overview of the basic quantum Monte Carlo methods, the forms and optimisation of wave functions, performing calculations within periodic boundary conditions, using pseudopotentials, excited-state calculations, sources of calculational inaccuracy, and calculating energy differences and forces

Quantum Monte Carlo study of a positron in an electron gas

Quantum Monte Carlo calculations of the relaxation energy, pair-correlation function, and annihilating-pair momentum density are presented for a positron immersed in a homogeneous electron gas. We find smaller relaxation energies and contact pair-correlation functions in the important low-density regime than predicted by earlier studies. Our annihilating-pair momentum densities have almost zero weight above the Fermi momentum due to the cancellation of electron-electron and electron-positron correlation effects

Framework for constructing generic Jastrow correlation factors

We have developed a flexible framework for constructing Jastrow factors which allows for the introduction of terms involving arbitrary numbers of particles. The use of various three- and four-body Jastrow terms in quantum Monte Carlo calculations is investigated, including a four-body van der Waals-like term, and anisotropic terms. We have tested these Jastrow factors on one- and two-dimensional homogeneous electron gases, the Be, B, and O atoms, and the BeH, H$_2$O, N$_2$, and H$_2$ molecules. Our optimized Jastrow factors retrieve more than 90% of the fixed-node diffusion Monte Carlo correlation energy in variational Monte Carlo for each system studied.Comment: 17 pages, 4 figure

Inhomogeneous backflow transformations in quantum Monte Carlo calculations

An inhomogeneous backflow transformation for many-particle wave functions is presented and applied to electrons in atoms, molecules, and solids. We report variational and diffusion quantum Monte Carlo VMC and DMC energies for various systems and study the computational cost of using backflow wave functions. We find that inhomogeneous backflow transformations can provide a substantial increase in the amount of correlation energy retrieved within VMC and DMC calculations. The backflow transformations significantly improve the wave functions and their nodal surfaces.Comment: ~20 pages, 11 figure

Smoking-attributable mortality in Portugal and its regions in 2019

Funding Information: This research was supported by the Instituto de Salud Carlos III (ISCIII) through the project “ PI19/00288 ″ and co-funded by the European Union . Publisher Copyright: © 2023 Sociedade Portuguesa de PneumologiaIntroduction and objectives: Timely regional-specific estimates of smoking-attributable mortality (SAM) are crucial for healthcare planning and tobacco control advocacy. Currently, this information is lacking in Portugal. The aim of this study was to estimate SAM by region in 2019 among the Portuguese population aged ≥35 years. Methods: SAM was estimated using an independent-prevalence method. Observed mortality was obtained from Portugal Statistics; lung cancer mortality rates in smokers and never-smokers from the Cancer Prevention Study I-II and updated relative risks from five contemporary US cohort studies. SAM was estimated for each NUTS-II region by sex, age, and cause of death. Crude SAM rates, sex and age-specific rates, and age-adjusted rates were calculated using the direct method. Results: In 2019, tobacco consumption caused 13,847 deaths, representing 12.3% of total mortality among the Portuguese population aged ≥35 years. Of the total SAM, 71.2% occurred in men and 22.2% in those under 65 years; 42.5% was due to cancer, 35.4% to cardiovascular and metabolic diseases, and 22.2% to respiratory diseases. SAM greatly varied among regions from 2.1% in Madeira to 36.2% in the North region. In men, cancer was the leading cause of death in all regions, while in women it was cardiovascular and metabolic diseases. Conclusion: In Portugal, tobacco-mortality burden is high and varies significantly by region, sex and age. Therefore, estimates disaggregated by sociodemographic data and region may better support decision-makers while tailoring and implementing tobacco control policies addressing health population needs. The apparent lower tobacco burden among women and in some Portuguese regions may dramatically rise in the near future. This and the high SAM in Portugal, particularly in some regions, highlights the need to accelerate tobacco control both at national and regional levels.publishersversioninpres

Economía feminista

El propósito inicial de este PAP, por ser el primer acercamiento a escenario, era realizar el diagnóstico de este, así como la introducción y asentamiento a los principios de la economía social y feminista, objetivos que fueron alcanzados. Este documento recopila la experiencia del Proyecto de Aplicación Profesional de Economía Feminista en el ciclo Otoño 2022 cuyo escenario fue el Centro de Atención y Desarrollo Integral del Formador (CADIF), se expone el proceso de diagnóstico que se tuvo al grupo para la co-creación de una propuesta de trabajo para el ciclo Primavera 2023. Fue relevante hacer el diagnóstico del grupo debido a que las personas que lo conformaban residen en diferentes zonas del Área Metropolitana de Guadalajara y sus condiciones socioeconómicas variaba bastante. Con base a los resultados del diagnóstico que arrojaron las necesidades de las y los beneficiarios se concluyeron 4 bloques específicos a trabajar en el ciclo Primavera 2023: control financiero, imagen y marketing, comportamiento organizacional y fundamentos legales.ITESO, A.C

Distribution and outcomes of a phenotype-based approach to guide COPD management: Results from the CHAIN cohort

Rationale: The Spanish guideline for COPD (GesEPOC) recommends COPD treatment according to four clinical phenotypes: non-exacerbator phenotype with either chronic bronchitis or emphysema (NE), asthma-COPD overlap syndrome (ACOS), frequent exacerbator phenotype with emphysema (FEE) or frequent exacerbator phenotype with chronic bronchitis (FECB). However, little is known on the distribution and outcomes of the four suggested phenotypes. Objective: We aimed to determine the distribution of these COPD phenotypes, and their relation with one-year clinical outcomes. Methods: We followed a cohort of well-characterized patients with COPD up to one-year. Baseline characteristics, health status (CAT), BODE index, rate of exacerbations and mortality up to one year of follow-up were compared between the four phenotypes. Results: Overall, 831 stable COPD patients were evaluated. They were distributed as NE, 550 (66.2%); ACOS, 125 (15.0%); FEE, 38 (4.6%); and FECB, 99 (11.9%); additionally 19 (2.3%) COPD patients with frequent exacerbations did not fulfill the criteria for neither FEE nor FECB. At baseline, there were significant differences in symptoms, FEV1 and BODE index (all p<0.05). The FECB phenotype had the highest CAT score (17.1±8.2, p<0.05 compared to the other phenotypes). Frequent exacerbator groups (FEE and FECB) were receiving more pharmacological treatment at baseline, and also experienced more exacerbations the year after (all p<0.05) with no differences in one-year mortality. Most of NE (93%) and half of exacerbators were stable after one year. Conclusions: There is an uneven distribution of COPD phenotypes in stable COPD patients, with significant differences in demographics, patient-centered outcomes and health care resources use