Under the Kigali Amendment to the Montreal Protocol, new controls are being implemented to reduce emissions of HFC-23 (CHFFormula: see text), a by-product during the manufacture of HCFC-22 ...(CHClFFormula: see text). Starting in 2015, China and India, who dominate global HCFC-22 production (75% in 2017), set out ambitious programs to reduce HFC-23 emissions. Here, we estimate that these measures should have seen global emissions drop by 87% between 2014 and 2017. Instead, atmospheric observations show that emissions have increased and in 2018 were higher than at any point in history (15.9 Formula: see text). Given the magnitude of the discrepancy between expected and observation-inferred emissions, it is likely that the reported reductions have not fully materialized or there may be substantial unreported production of HCFC-22, resulting in unaccounted-for HFC-23 by-product emissions. The difference between reported and observation-inferred estimates suggests that an additional ~309 Tg Formula: see text-equivalent emissions were added to the atmosphere between 2015 and 2017.
On the frequency module of the hull of a primitive substitution tiling Say-awen, April Lynne D.; Frettlöh, Dirk; De Las Peñas, Ma. Louise Antonette N.
Acta crystallographica. Section A, Foundations and advances,
January 2022, 2022-Jan-01, 2022-01-01, 20220101, Volume:
78, Issue:
1
Journal Article
Peer reviewed
Open access
Understanding the properties of tilings is of increasing relevance to the study of aperiodic tilings and tiling spaces. This work considers the statistical properties of the hull of a primitive ...substitution tiling, where the hull is the family of all substitution tilings with respect to the substitution. A method is presented on how to arrive at the frequency module of the hull of a primitive substitution tiling (the minimal ‐module, where is the set of integers) containing the absolute frequency of each of its patches. The method involves deriving the tiling's edge types and vertex stars; in the process, a new substitution is introduced on a reconstructed set of prototiles.
As part of the study of aperiodic tilings and tiling spaces, the frequency module of the hull of a primitive substitution tiling is computed.
It is estimated that global anthropogenic carbon dioxide (CO2) emissions reduced by up to 12% at the start of 2020 compared to recent years due to the COVID-19 related downturn in economic activity. ...Despite the large decrease in CO2 emissions, no reduction in the trend in background atmospheric CO2 concentrations has been detected. So, how long would it take for sustained COVID-19 CO2 emission reductions to be detected in daily and monthly averaged local CO2 concentration measurements? CO2 concentration measurements for five measurement sites in the UK and Ireland are combined with meteorological numerical weather prediction data to build statistical models that can predict future CO2 concentrations. It is found that \(75\%\) of the observed daily variability can be explained by these simple models. Emission reduction scenario experiments using these simple models illustrate that large daily and seasonal variability in local CO2 concentrations precludes the rapid emergence of a detectable signal. COVID-19 magnitude emissions reductions would only be detectable in the daily CO2 concentrations after at least 38 months and in monthly CO2 concentrations after 11 months of sustained reductions. For monthly CO2 concentrations the time of emergence is similar for all sites since the seasonal variability is largely driven by non-local fluxes of CO2 between the terrestrial biosphere and the atmosphere. The COVID-19 CO2 anthropogenic emissions reductions are similar in magnitude to those that are required to meet the Paris Agreement target of keeping global temperatures below \(2\,^{\circ}\)C. This study demonstrates that, using measurements alone, there will be a considerable lag between changes in global anthropogenic emissions and a detected signal in local CO2 concentration trends. Thus, there is likely to be a delay of several years between changes in policy designed to meet CO2 anthropogenic emissions targets and our ability to detect the impact of these policies on CO2 concentrations using atmospheric measurements alone.
Primitive substitution tilings with rotational symmetries Say-awen, April Lynne D.; De Las Peñas, Ma. Louise Antonette N.; Frettlöh, Dirk
Acta crystallographica. Section A, Foundations and advances,
July 2018, 2018-Jul-01, 2018-07-01, 20180701, Volume:
74, Issue:
4
Journal Article
Peer reviewed
This work introduces the idea of symmetry order, which describes the rotational symmetry types of tilings in the hull of a given substitution. Definitions are given of the substitutions σ6 and σ7 ...which give rise to aperiodic primitive substitution tilings with dense tile orientations and which are invariant under six‐ and sevenfold rotations, respectively; the derivation of the symmetry orders of their hulls is also presented.
The idea of symmetry order, which describes the rotational symmetry types of tilings in the hull of a given substitution, is introduced. Two substitutions giving rise to six‐ and sevenfold rotation‐invariant tilings are also presented.
Summary Background Previous estimates have highlighted a large global burden of stillbirths, with an absence of reliable data from regions where most stillbirths occur. The Every Newborn Action Plan ...(ENAP) targets national stillbirth rates (SBRs) of 12 or fewer stillbirths per 1000 births by 2030. We estimate SBRs and numbers for 195 countries, including trends from 2000 to 2015. Methods We collated SBR data meeting prespecified inclusion criteria from national routine or registration systems, nationally representative surveys, and other data sources identified through a systematic review, web-based searches, and consultation with stillbirth experts. We modelled SBR (≥28 weeks' gestation) for 195 countries with restricted maximum likelihood estimation with country-level random effects. Uncertainty ranges were obtained through a bootstrap approach. Findings Data from 157 countries (2207 datapoints) met the inclusion criteria, a 90% increase from 2009 estimates. The estimated average global SBR in 2015 was 18·4 per 1000 births, down from 24·7 in 2000 (25·5% reduction). In 2015, an estimated 2·6 million (uncertainty range 2·4–3·0 million) babies were stillborn, giving a 19% decline in numbers since 2000 with the slowest progress in sub-Saharan Africa. 98% of all stillbirths occur in low-income and middle-income countries; 77% in south Asia and sub-Saharan Africa. Interpretation Progress in reducing the large worldwide stillbirth burden remains slow and insufficient to meet national targets such as for ENAP. Stillbirths are increasingly being counted at a local level, but countries and the global community must further improve the quality and comparability of data, and ensure that this is more clearly linked to accountability processes including the Sustainable Development Goals. Funding Save the Children's Saving Newborn Lives programme to The London School of Hygiene & Tropical Medicine.
Abstract
It is estimated that global anthropogenic carbon dioxide (CO
2
) emissions reduced by up to 12% at the start of 2020 compared to recent years due to the COVID-19 related downturn in economic ...activity. Despite the large decrease in CO
2
emissions, no reduction in the trend in background atmospheric CO
2
concentrations has been detected. So, how long would it take for sustained COVID-19 CO
2
emission reductions to be detected in daily and monthly averaged local CO
2
concentration measurements? CO
2
concentration measurements for five measurement sites in the UK and Ireland are combined with meteorological numerical weather prediction data to build statistical models that can predict future CO
2
concentrations. It is found that
75
%
of the observed daily variability can be explained by these simple models. Emission reduction scenario experiments using these simple models illustrate that large daily and seasonal variability in local CO
2
concentrations precludes the rapid emergence of a detectable signal. COVID-19 magnitude emissions reductions would only be detectable in the daily CO
2
concentrations after at least 38 months and in monthly CO
2
concentrations after 11 months of sustained reductions. For monthly CO
2
concentrations the time of emergence is similar for all sites since the seasonal variability is largely driven by non-local fluxes of CO
2
between the terrestrial biosphere and the atmosphere. The COVID-19 CO
2
anthropogenic emissions reductions are similar in magnitude to those that are required to meet the Paris Agreement target of keeping global temperatures below
2
°
C. This study demonstrates that, using measurements alone, there will be a considerable lag between changes in global anthropogenic emissions and a detected signal in local CO
2
concentration trends. Thus, there is likely to be a delay of several years between changes in policy designed to meet CO
2
anthropogenic emissions targets and our ability to detect the impact of these policies on CO
2
concentrations using atmospheric measurements alone.
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