2D Modelling of Mechanical Stress Evolution and Electromigration in Confined Aluminium Interconnects

A complete description for mechanical stress evolution and electromigration in confined Al interconnects, taking into account the microstructure features, is presented in this paper. In the last years there were proposed several 1D models for the time-dependent evolution of the mechanical stress in Al interconnect lines, since the time to failure of the line can be related to the time a critical value of the stress is reached. The present paper extends and improves the existing models in 2D using a two dimensional simulator based on finite element method. Also, the model makes an attempt to relate the stress/vacancy concentration evolution with the early resistance change of the Al lin

Early resistance change and stress/electromigrationmodeling in aluminium interconnects

A complete description for early resistance change and two dimensional simulation of mechanical stress evolution in confined Al interconnects, related to the electromigration, is given in this paper. The model, combines the stress/ vacancy concentration evolution with the early resistance change of the Al line, that could be [1] a fast technique for prediction of the MTF of a line compared to the conventional (accelerated) tests

Early resistance change and stress/electromigration evolution in near bamboo interconnects

A complete description for early resistance change and mechanical stress evolution in near-bamboo interconnects, related to the electromigration, is given in this paper. The proposed model, for the first time, combines the stress/vacancy concentration evolution with the early resistance change of the Al line with a near-bamboo microstructure, which has been proven to be a fast technique for prediction of the MTF of a line compared to the conventional (accelerated) stres

The growing season greenhouse gas balance of a continental tundra site in the Indigirka lowlands, NE Siberia.

Carbon dioxide and methane fluxes were measured at a tundra site near Chokurdakh, in the lowlands of the Indigirka river in north-east Siberia. This site is one of the few stations on Russian tundra and it is different from most other tundra flux stations in its continentality. A suite of methods was applied to determine the fluxes of NEE, GPP, <i>R</i><sub>eco</sub> and methane, including eddy covariance, chambers and leaf cuvettes. Net carbon dioxide fluxes were high compared with other tundra sites, with NEE=−92 g C m<sup>−2</sup> yr<sup>−1</sup>, which is composed of an <i>R</i><sub>eco</sub>=+141 g C m<sup>−2</sup> yr<sup>−1</sup> and GPP=−232 g C m<sup>−2</sup> yr<sup>−1</sup>. This large carbon dioxide sink may be explained by the continental climate, that is reflected in low winter soil temperatures (−14°C), reducing the respiration rates, and short, relatively warm summers, stimulating high photosynthesis rates. Interannual variability in GPP was dominated by the frequency of light limitation (<i>R<sub>g</sub></i><200 W m<sup>−2</sup>), whereas <i>R</i><sub>eco</sub> depends most directly on soil temperature and time in the growing season, which serves as a proxy of the combined effects of active layer depth, leaf area index, soil moisture and substrate availability. The methane flux, in units of global warming potential, was +28 g C-CO<sub>2</sub>e m<sup>−2</sup> yr<sup>−1</sup>, so that the greenhouse gas balance was −64 g C-CO<sub>2</sub>e m<sup>−2</sup> yr<sup>−1</sup>. Methane fluxes depended only slightly on soil temperature and were highly sensitive to hydrological conditions and vegetation composition

The consolidated European synthesis of CH4 and N2O emissions for the European Union and United Kingdom: 1990–2017

Reliable quantification of the sources and sinks of greenhouse gases, together with trends and uncertainties, is essential to monitoring the progress in mitigating anthropogenic emissions under the Paris Agreement. This study provides a consolidated synthesis of CH4 and N2O emissions with consistently derived state-of-the-art bottom-up (BU) and top-down (TD) data sources for the European Union and UK (EU27 + UK). We integrate recent emission inventory data, ecosystem process-based model results and inverse modeling estimates over the period 1990-2017. BU and TD products are compared with European national greenhouse gas inventories (NGHGIs) reported to the UN climate convention UNFCCC secretariat in 2019. For uncertainties, we used for NGHGIs the standard deviation obtained by varying parameters of inventory calculations, reported by the member states (MSs) following the recommendations of the IPCC Guidelines. For atmospheric inversion models (TD) or other inventory datasets (BU), we defined uncertainties from the spread between different model estimates or model-specific uncertainties when reported. In comparing NGHGIs with other approaches, a key source of bias is the activities included, e.g., anthropogenic versus anthropogenic plus natural fluxes. In inversions, the separation between anthropogenic and natural emissions is sensitive to the geospatial prior distribution of emissions. Over the 2011-2015 period, which is the common denominator of data availability between all sources, the anthropogenic BU approaches are directly comparable, reporting mean emissions of 20.8 Tg CH4 yr-1 (EDGAR v5.0) and 19.0 Tg CH4 yr-1 (GAINS), consistent with the NGHGI estimates of 18.9 ± 1.7 Tg CH4 yr-1. The estimates of TD total inversions give higher emission estimates, as they also include natural emissions. Over the same period regional TD inversions with higher-resolution atmospheric transport models give a mean emission of 28.8 Tg CH4 yr-1. Coarser-resolution global TD inversions are consistent with regional TD inversions, for global inversions with GOSAT satellite data (23.3 Tg CH4 yr-1) and surface network (24.4 Tg CH4 yr-1). The magnitude of natural peatland emissions from the JSBACH-HIMMELI model, natural rivers and lakes emissions, and geological sources together account for the gap between NGHGIs and inversions and account for 5.2 Tg CH4 yr-1. For N2O emissions, over the 2011-2015 period, both BU approaches (EDGAR v5.0 and GAINS) give a mean value of anthropogenic emissions of 0.8 and 0.9 Tg N2O yr-1, respectively, agreeing with the NGHGI data (0.9 ± 0.6 Tg N2O yr-1). Over the same period, the average of the three total TD global and regional inversions was 1.3 ± 0.4 and 1.3 ± 0.1 Tg N2O yr-1, respectively. The TD and BU comparison method defined in this study can be operationalized for future yearly updates for the calculation of CH4 and N2O budgets both at the EU+UK scale and at the national scale. The referenced datasets related to figures are visualized at. (Petrescu et al., 2020b)

Rising rural body-mass index is the main driver of the global obesity epidemic in adults

Body-mass index (BMI) has increased steadily in most countries in parallel with a rise in the proportion of the population who live in cities 1,2 . This has led to a widely reported view that urbanization is one of the most important drivers of the global rise in obesity 3�6 . Here we use 2,009 population-based studies, with measurements of height and weight in more than 112 million adults, to report national, regional and global trends in mean BMI segregated by place of residence (a rural or urban area) from 1985 to 2017. We show that, contrary to the dominant paradigm, more than 55 of the global rise in mean BMI from 1985 to 2017�and more than 80 in some low- and middle-income regions�was due to increases in BMI in rural areas. This large contribution stems from the fact that, with the exception of women in sub-Saharan Africa, BMI is increasing at the same rate or faster in rural areas than in cities in low- and middle-income regions. These trends have in turn resulted in a closing�and in some countries reversal�of the gap in BMI between urban and rural areas in low- and middle-income countries, especially for women. In high-income and industrialized countries, we noted a persistently higher rural BMI, especially for women. There is an urgent need for an integrated approach to rural nutrition that enhances financial and physical access to healthy foods, to avoid replacing the rural undernutrition disadvantage in poor countries with a more general malnutrition disadvantage that entails excessive consumption of low-quality calories. © 2019, The Author(s)

The Modeling of Resistance Changes in the Early Phase of Electromigration

Sensitive measurements of the evolution of the resistance of aluminum based metallisation stripes that have been electrically stressed with large current densities show a rather unpredictable initial change followed by a more or less linear increase (less than 1%) for a considerable period of time. Ultimately, breakdown will occur preceded by an erratic behavior of the resistance. This paper reviews existing models for these early changes. It reviews the importance of a generation term for vacancies separate from a divergence of flux term in the explanation of small resistance changes in these models and proposes an alternative view that explains the linear behavior of the resistance change and can also incorporate a variety of initial changes depending on initial mechanical stress conditions. In this model it is assumed that electron wind can create vacancies in the grain boundary regions that are further redistributed because of the electrical current. In this creation process less mobile damage is created, that contributes to the scattering of electrons and thus increases the resistance