The PMIP4 contribution to CMIP6 – Part 2: two interglacials, scientific objective and experimental design for Holocene and last interglacial simulations

Two interglacial epochs are included in the suite of Paleoclimate Modeling Intercomparison Project (PMIP4) simulations in the Coupled Model Intercomparison Project (CMIP6). The experimental protocols for Tier 1 simulations of the mid-Holocene (midHolocene, 6000 years before present) and the Last Interglacial (lig127k, 127,000 years before present) are described here. These equilibrium simulations are designed to examine the impact of changes in orbital forcing at times when atmospheric greenhouse gas levels were similar to those of the preindustrial period and the continental configurations were almost identical to modern. These simulations test our understanding of the interplay between radiative forcing and atmospheric circulation, and the connections among large-scale and regional climate changes giving rise to phenomena such as land-sea contrast and high-latitude amplification in temperature changes, and responses of the monsoons, as compared to today. They also provide an opportunity, through carefully designed additional CMIP6 Tier 2 and Tier 3 sensitivity experiments of PMIP4, to quantify the strength of atmosphere, ocean, cryosphere, and land-surface feedbacks. Sensitivity experiments are proposed to investigate the role of freshwater forcing in triggering abrupt climate changes within interglacial epochs. These feedback experiments naturally lead to a focus on climate evolution during interglacial periods, which will be examined through transient experiments. Analyses of the sensitivity simulations will also focus on interactions between extratropical and tropical circulation, and the relationship between changes in mean climate state and climate variability on annual to multi-decadal timescales. The comparative abundance of paleoenvironmental data and of quantitative climate reconstructions for the Holocene and Last Interglacial make these two epochs ideal candidates for systematic evaluation of model performance, and such comparisons will shed new light on the importance of external feedbacks (e.g., vegetation, dust) and the ability of state-of-the-art models to simulate climate changes realistically

Mapping infectious disease hospital surge threats to lessons learnt in Singapore: a systems analysis and development of a framework to inform how to DECIDE on planning and response strategies.

BACKGROUND: Hospital usage and service demand during an Infectious Disease (ID) outbreak can tax the health system in different ways. Herein we conceptualize hospital surge elements, and lessons learnt from such events, to help build appropriately matched responses to future ID surge threats. METHODS: We used the Interpretive Descriptive qualitative approach. Interviews (n = 35) were conducted with governance and public health specialists; hospital based staff; and General Practitioners. Key policy literature in tandem with the interview data were used to iteratively generate a Hospital ID Surge framework. We anchored our narrative account within this framework, which is used to structure our analysis. RESULTS: A spectrum of surge threats from combinations of capacity (for crowding) and capability (for treatment complexity) demands were identified. Starting with the Pyramid scenario, or an influx of high screening rates flooding Emergency Departments, alongside fewer and manageable admissions; the Reverse-Pyramid occurs when few cases are screened and admitted but those that are, are complex; during a 'Black' scenario, the system is overburdened by both crowding and complexity. The Singapore hospital system is highly adapted to crowding, functioning remarkably well at constant near-full capacity in Peacetime and resilient to Endemic surges. We catalogue 26 strategies from lessons learnt relating to staffing, space, supplies and systems, crystalizing institutional memory. The DECIDE model advocates linking these strategies to types of surge threats and offers a step-by-step guide for coordinating outbreak planning and response. CONCLUSIONS: Lack of a shared definition and decision making of surge threats had rendered the procedures somewhat duplicative. This burden was paradoxically exacerbated by a health system that highly prizes planning and forward thinking, but worked largely in silo until an ID crisis hit. Many such lessons can be put into play to further strengthen our current hospital governance and adapted to more diverse settings

Interlaboratory Comparison of δ13C and δD Measurements of Atmospheric CH4 for Combined Use of Data Sets from Different Laboratories

We report results from a worldwide interlaboratory comparison of samples among laboratories that measure (or measured) stable carbon and hydrogen isotope ratios of atmospheric CH4 (δ13C-CH4 and δD-CH4). The offsets among the laboratories are larger than the measurement reproducibility of individual laboratories. To disentangle plausible measurement offsets, we evaluated and critically assessed a large number of intercomparison results, some of which have been documented previously in the literature. The results indicate significant offsets of δ13C-CH4 and δD- CH4 measurements among data sets reported from different laboratories; the differences among laboratories at modern atmospheric CH4 level spread over ranges of 0.5 ‰ for δ13C-CH4 and 13 ‰ for δD-CH4. The intercomparison results summarized in this study may be of help in future at tempts to harmonize δ13C-CH4 and δD-CH4 data sets from different laboratories in order to jointly incorporate them into modelling studies. However, establishing a merged data set, which includes δ13C-CH4 and δD-CH4 data from multiple laboratories with desirable compatibility, is still challenging due to differences among laboratories in instrument settings, correction methods, traceability to reference materials and long-term data management. Further efforts are needed to identify causes of the interlaboratory measurement offsets and to decrease those to move towards the best use of available δ13C-CH4 and δD-CH4 data sets

Genetics, chromatin diminution, and sex chromosome evolution in the parasitic nematode genus strongyloides

BACKGROUND: When chromatin diminution occurs during a cell division a portion of the chromatin is eliminated, resulting in daughter cells with a smaller amount of genetic material. In the parasitic roundworms Ascaris and Parascaris, chromatin diminution creates a genetic difference between the soma and the germline. However, the function of chromatin diminution remains a mystery, because the vast majority of the eliminated DNA is noncoding. Within the parasitic roundworm genus Strongyloides, S. stercoralis (in man) and S. ratti (in rat) employ XX/XO sex determination, but the situation in S. papillosus (in sheep) is different but controversial. RESULTS: We demonstrate genetically that S. papillosus employs sex-specific chromatin diminution to eliminate an internal portion of one of the two homologs of one chromosome pair in males. Contrary to ascarids, the eliminated DNA in S. papillosus contains a large number of genes. We demonstrate that the region undergoing diminution is homologous to the X chromosome of the closely related S. ratti. The flanking regions, which are not diminished, are homologous to the S. ratti autosome number I. Furthermore, we found that the diminished chromosome is not incorporated into sperm, resulting in a male-specific transmission ratio distortion. CONCLUSIONS: Our data indicate that on the evolutionary path to S. papillosus, the X chromosome fused with an autosome. Chromatin diminution serves to functionally restore an XX/XO sex-determining system. A consequence of the fusion and the process that copes with it is a transmission ratio distortion in males for certain loci

Interlaboratory comparison of δ13C and δD measurements of atmospheric CH4 for combined use of data sets from different laboratories

We report results from a worldwide interlaboratory comparison of samples among laboratories that measure (or measured) stable carbon and hydrogen isotope ratios of atmospheric CH4 (δ13C-CH4 and δD-CH4). The offsets among the laboratories are larger than the measurement reproducibility of individual laboratories. To disentangle plausible measurement offsets, we evaluated and critically assessed a large number of intercomparison results, some of which have been documented previously in the literature. The results indicate significant offsets of δ13C-CH4 and δDCH4 measurements among data sets reported from different laboratories; the differences among laboratories at modern atmospheric CH4 level spread over ranges of 0.5‰ for δ13C-CH4 and 13‰ for δD-CH4. The intercomparison results summarized in this study may be of help in future attempts to harmonize δ13C-CH4 and δD-CH4 data sets from different laboratories in order to jointly incorporate them into modelling studies. However, establishing a merged data set, which includes δ13C-CH4 and δD-CH4 data from multiple laboratories with desirable compatibility, is still challenging due to differences among laboratories in instrument settings, correction methods, traceability to reference materials and long-term data management. Further efforts are needed to identify causes of the interlaboratory measurement offsets and to decrease those to move towards the best use of available δ13C-CH4 and δD-CH4 data sets.JRC.C.5-Air and Climat

Interlaboratory comparison of δ¹³C and δD measurements of atmospheric CH₄ for combined use of data sets from different laboratories

We report results from a worldwide interlaboratory comparison of samples among laboratories that measure (or measured) stable carbon and hydrogen isotope ratios of atmospheric CH₄ (δ¹³C-CH₄ and δD-CH₄). The offsets among the laboratories are larger than the measurement reproducibility of individual laboratories. To disentangle plausible measurement offsets, we evaluated and critically assessed a large number of intercomparison results, some of which have been documented previously in the literature. The results indicate significant offsets of δ¹³C-CH₄ and δD-CH₄ measurements among data sets reported from different laboratories; the differences among laboratories at modern atmospheric CH₄ level spread over ranges of 0.5 ‰ for δ¹³C-CH₄ and 13 ‰ for δD-CH₄. The intercomparison results summarized in this study may be of help in future attempts to harmonize δ¹³C-CH₄ and δD-CH₄ data sets from different laboratories in order to jointly incorporate them into modelling studies. However, establishing a merged data set, which includes δ¹³C-CH₄ and δD-CH₄ data from multiple laboratories with desirable compatibility, is still challenging due to differences among laboratories in instrument settings, correction methods, traceability to reference materials and long-term data management. Further efforts are needed to identify causes of the interlaboratory measurement offsets and to decrease those to move towards the best use of available δ¹³C-CH₄ and δD-CH₄ data sets