175 research outputs found
Effect of Ce and Sb on Primary Graphite Growth in Cast Irons
It is well-known that if certain trace elements are present in cast iron melts the morphology of the graphite precipitates can be altered. In order to understand the effect of doping elements on primary growth of graphite, pure Fe–Sb alloys were prepared by induction melting. They were then placed in graphite crucibles and heated to a temperature above the Fe–C eutectic so that the charge became saturated in carbon and melted. To obtain Fe–Ce alloys, metallic Ce was added at the bottom of a graphite crucible and covered with iron, and then heated as for the Fe–Sb charge. In both cases, the melt was then cooled and held slightly above the eutectic temperature so that primary graphite crystals, which had nucleated on the crucible walls and then detached from it, could grow freely in the melt. The influence of the added elements on graphite growth was revealed by the change in the shape and distribution of the crystals compared to those obtained in similar experiments carried out with pure Fe. The experiments were made in air and vacuum so as to point out possible interactions between the elements present in the melt and oxygen
Cell arrest and cell death in mammalian preimplantation development
The causes, modes, biological role and prospective significance of cell death in preimplantation development in humans and other mammals are still poorly understood. Early bovine embryos represent a very attractive experimental model for the investigation of this fundamental and important issue.
To obtain reference data on the temporal and spatial occurrence of cell death in early bovine embryogenesis, three-dimensionally preserved embryos of different ages and stages of development up to hatched blastocysts were examined in toto by confocal laser scanning microscopy. In parallel, transcript abundance profiles for selected apoptosis-related genes were analyzed by real-time reverse transcriptase-polymerase chain reaction. Our study documents that in vitro as well as in vivo, the first four cleavage cycles are prone to a high failure rate including different types of permanent cell cycle arrest and subsequent non-apoptotic blastomere death. In vitro produced and in vivo derived blastocysts showed a significant incidence of cell death in the inner cell mass (ICM), but only in part with morphological features of apoptosis. Importantly, transcripts for CASP3, CASP9, CASP8 and FAS/FASLG were not detectable or found at very low abundances.
In vitro and in vivo, errors and failures of the first and the next three cleavage divisions frequently cause immediate embryo death or lead to aberrant subsequent development, and are the main source of developmental heterogeneity. A substantial occurrence of cell death in the ICM even in fast developing blastocysts strongly suggests a regular developmentally controlled elimination of cells, while the nature and mechanisms of ICM cell death are unclear. Morphological findings as well as transcript levels measured for important apoptosis-related genes are in conflict with the view that classical caspase-mediated apoptosis is the major cause of cell death in early bovine development
Land–atmosphere interactions in sub-polar and alpine climates in the CORDEX Flagship Pilot Study Land Use and Climate Across Scales (LUCAS) models – Part 2: The role of changing vegetation
Land cover in sub-polar and alpine regions of northern and eastern Europe have already begun changing due to natural and anthropogenic changes such as afforestation. This will impact the regional climate and hydrology upon which societies in these regions are highly reliant. This study aims to identify the impacts of afforestation/reforestation (hereafter afforestation) on snow and the snow-albedo effect and highlight potential improvements for future model development. The study uses an ensemble of nine regional climate models for two different idealised experiments covering a 30-year period; one experiment replaces most land cover in Europe with forest, while the other experiment replaces all forested areas with grass. The ensemble consists of nine regional climate models composed of different combinations of five regional atmospheric models and six land surface models. Results show that afforestation reduces the snow-albedo sensitivity index and enhances snowmelt. While the direction of change is robustly modelled, there is still uncertainty in the magnitude of change. The greatest differences between models emerge in the snowmelt season. One regional climate model uses different land surface models which shows consistent changes between the three simulations during the accumulation period but differs in the snowmelt season. Together these results point to the need for further model development in representing both grass–snow and forest–snow interactions during the snowmelt season. Pathways to accomplishing this include (1) a more sophisticated representation of forest structure, (2) kilometre-scale simulations, and (3) more observational studies on vegetation–snow interactions in northern Europe
Land–atmosphere interactions in sub-polar and alpine climates in the CORDEX flagship pilot study Land Use and Climate Across Scales (LUCAS) models – Part 1: Evaluation of the snow-albedo effect
Seasonal snow cover plays a major role in the climate system of the Northern Hemisphere via its effect on land surface albedo and fluxes. In climate models the parameterization of interactions between snow and atmosphere remains a source of uncertainty and biases in the representation of local and global climate. Here, we evaluate the ability of an ensemble of regional climate models (RCMs) coupled with different land surface models to simulate snow–atmosphere interactions over Europe in winter and spring. We use a previously defined index, the snow-albedo sensitivity index (SASI), to quantify the radiative forcing associated with snow cover anomalies. By comparing RCM-derived SASI values with SASI calculated from reanalyses and satellite retrievals, we show that an accurate simulation of snow cover is essential for correctly reproducing the observed forcing over middle and high latitudes in Europe. The choice of parameterizations, and primarily the choice of the land surface model, strongly influences the representation of SASI as it affects the ability of climate models to simulate snow cover accurately. The degree of agreement between the datasets differs between the accumulation and ablation periods, with the latter one presenting the greatest challenge for the RCMs. Given the dominant role of land surface processes in the simulation of snow cover during the ablation period, the results suggest that, during this time period, the choice of the land surface model is more critical for the representation of SASI than the atmospheric model
A decentralized approach to model national and global food and land use systems
The achievement of several sustainable development goals and the Paris Climate Agreement depends on rapid progress towards sustainable food and land systems in all countries. We have built a flexible, collaborative modeling framework to foster the development of national pathways by local research teams and their integration up to global scale. Local researchers independently customize national models to explore mid-century pathways of the food and land use system transformation in collaboration with stakeholders. An online platform connects the national models, iteratively balances global exports and imports, and aggregates results to the global level. Our results show that actions toward greater sustainability in countries could sum up to 1 Mha net forest gain per year, 950 Mha net gain in the land where natural processes predominate, and an increased CO2 sink of 3.7 GtCO2e yr−1 over the period 2020-2050 compared to current trends, while average food consumption per capita remains above the adequate food requirements in all countries. We show examples of how the global linkage impacts national results and how different assumptions in national pathways impact global results. This modeling setup acknowledges the broad heterogeneity of socio-ecological contexts and the fact that people who live in these different contexts should be empowered to design the future they want. But it also demonstrates to local decision-makers the interconnectedness of our food and land use system and the urgent need for more collaboration to converge local and global priorities.Fil: Mosnier, Aline. Sustainable Development Solutions Network; FranciaFil: Javalera Rincon, Valeria. International Institute For Applied Systems Analysis, Laxenburg; AustriaFil: Jones, Sarah K. Alliance of Bioversity International; FranciaFil: Andrew, Robbie. Center for International Climate Research; NoruegaFil: Bai, Zhaohai. Chinese Academy of Sciences; República de ChinaFil: Baker, Justin. North Carolina State University; Estados UnidosFil: Basnet, Shyam. Stockholm Resilience Centre; SueciaFil: Boer, Rizaldi. Bogor Agricultural University; IndonesiaFil: Chavarro, John. Geo-agro-environmental Sciences And Resources Research Center; ColombiaFil: Costa, Wanderson. Centro de Previsao de Tempo e Estudos Climáticos. Instituto Nacional de Pesquisas Espaciais; BrasilFil: Daloz, Anne Sophie. Center for International Climate Research; NoruegaFil: DeClerck, Fabrice A.. Alliance of Bioversity International; Francia. Stockholm Resilience Centre; SueciaFil: Diaz, Maria. Sustainable Development Solutions Network; FranciaFil: Douzal, Clara. Sustainable Development Solutions Network; FranciaFil: Howe Fan, Andrew Chiah. Sunway University; MalasiaFil: Fetzer, Ingo. Stockholm Resilience Centre; SueciaFil: Frank, Federico. Instituto Nacional de TecnologÃa Agropecuaria. Centro Regional Buenos Aires; ArgentinaFil: Gonzalez Abraham, Charlotte E.. University of California at San Diego; Estados UnidosFil: Habiburrachman, A. H. F.. Universitas Indonesia; IndonesiaFil: Immanuel, Gito. Stockholm Resilience Centre; SueciaFil: Harrison, Paula A.. Centre for Ecology & Hydrology; Reino UnidoFil: Imanirareba, Dative. Uganda Martyrs University; UgandaFil: Jha, Chandan. Indian Institute Of Management Ahmedabad; IndiaFil: Monjeau, Jorge Adrian. Fundación Bariloche; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas; ArgentinaFil: Vittis, Yiorgos. International Institute For Applied Systems Analysis; AustriaFil: Wade, Chris. North Carolina State University; Estados UnidosFil: Winarni, Nurul L.. Universitas Indonesia; IndonesiaFil: Woldeyes, Firew Bekele. Ethiopian Development Research Institute; EtiopÃaFil: Wu, Grace C.. University of California; Estados UnidosFil: Zerriffi, Hisham. University of British Columbia; Canad
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Cluster analysis of downscaled and explicitly simulated North Atlantic tropical cyclone tracks
A realistic representation of the North Atlantic tropical cyclone tracks is crucial as it allows, for example, explaining potential changes in US landfalling systems. Here we present a tentative study, which examines the ability of recent climate models to represent North Atlantic tropical cyclone tracks. Tracks from two types of climate models are evaluated: explicit tracks are obtained from tropical cyclones simulated in regional or global climate models with moderate to high horizontal resolution (1° to 0.25°), and downscaled tracks are obtained using a downscaling technique with large-scale environmental fields from a subset of these models. For both configurations, tracks are objectively separated into four groups using a cluster technique, leading to a zonal and a meridional separation of the tracks. The meridional separation largely captures the separation between deep tropical and sub-tropical, hybrid or baroclinic cyclones, while the zonal separation segregates Gulf of Mexico and Cape Verde storms. The properties of the tracks’ seasonality, intensity and power dissipation index in each cluster are documented for both configurations. Our results show that except for the seasonality, the downscaled tracks better capture the observed characteristics of the clusters. We also use three different idealized scenarios to examine the possible future changes of tropical cyclone tracks under 1) warming sea surface temperature, 2) increasing carbon dioxide, and 3) a combination of the two. The response to each scenario is highly variable depending on the simulation considered. Finally, we examine the role of each cluster in these future changes and find no preponderant contribution of any single cluster over the others
Cross-European challenges for multi-risk assessment and management: insights from the first two years of MYRIAD-EU
Inhibitor of apoptosis proteins, NAIP, cIAP1 and cIAP2 expression during macrophage differentiation and M1/M2 polarization
Monocytes and macrophages constitute the first line of defense of the immune system
against external pathogens. Macrophages have a highly plastic phenotype depending on
environmental conditions; the extremes of this phenotypic spectrum are a pro-inflammatory
defensive role (M1 phenotype) and an anti-inflammatory tissue-repair one (M2 phenotype).
The Inhibitor of Apoptosis (IAP) proteins have important roles in the regulation of several cellular
processes, including innate and adaptive immunity. In this study we have analyzed the
differential expression of the IAPs, NAIP, cIAP1 and cIAP2, during macrophage differentiation
and polarization into M1 or M2. In polarized THP-1 cells and primary human macrophages,
NAIP is abundantly expressed in M2 macrophages, while cIAP1 and cIAP2 show
an inverse pattern of expression in polarized macrophages, with elevated expression levels
of cIAP1 in M2 and cIAP2 preferentially expressed in M1. Interestingly, treatment with the
IAP antagonist SMC-LCL161, induced the upregulation of NAIP in M2, the downregulation
of cIAP1 in M1 and M2 and an induction of cIAP2 in M1 macrophages.This work was supported by Universidad
de Granada, Plan Propio 2015;#P3B: FAM, VMC
(http://investigacion.ugr.es/pages/planpropio/2015/
resoluciones/p3b_def_28072015); Universidad
de Granada CEI BioTic;#CAEP2-84: VMC (http://
biotic.ugr.es/pages/resolucionprovisional
enseaanzapractica22demayo/!); and Canadian nstitutes of Health Research;#231421, #318176,
#361847: STB, ECL, RK (http://www.cihr-irsc.gc.
ca/e/193.html). The funders had no role in study
design, data collection and analysis, decision to
publish, or preparation of the manuscript
Challenges in assessing and managing multi-hazard risks: A European stakeholders perspective
The latest evidence suggests that multi-hazards and their interrelationships (e.g., triggering, compound, and consecutive hazards) are becoming more frequent across Europe, underlying a need for resilience building by moving from single-hazard-focused to multi-hazard risk assessment and management. Although significant advancements were made in our understanding of these events, mainstream practice is still focused on risks due to single hazards (e.g., flooding, earthquakes, droughts), with a limited understanding of the stakeholder needs on the ground. To overcome this limitation, this paper sets out to understand the challenges for moving towards multi-hazard risk management through the perspective of European stakeholders. Based on five workshops across different European pilots (Danube Region, Veneto Region, Scandinavia, North Sea, and Canary Islands) and an expert workshop, we identify five prime challenges: i) governance, ii) knowledge of multi-hazards and multi-risks, iii) existing approaches to disaster risk management, iv) translation of science to policy and practice, and v) lack of data. These challenges are inherently linked and cannot be tackled in isolation with path dependency posing a significant hurdle in transitioning from single- to multi-hazard risk management. Going forward, we identify promising approaches for overcoming some of the challenges, including emerging approaches for multi-hazard characterisation, a common understanding of terminology, and a comprehensive framework for guiding multi-hazard risk assessment and management. We argue for a need to think beyond natural hazards and include other threats in creating a comprehensive overview of multi-hazard risks, as well as promoting thinking of multi-hazard risk reduction in the context of larger development goals
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