3,154 research outputs found
The Prospect of Global Environmental Relativities After an Anthropocene Tipping Point
While there is vigorous debate on whether the Anthropocene epoch began in 1800, as originally proposed, less attention has been paid to the transition from Stage 2 of the existing three stage chronology, in which carbon dioxide emissions accelerated after 1945, to Stage 3, in which after 2015 acceleration is expected to reach criticality, and the Earth System is predicted to pass through an irreversible ātipping pointā to a warmer state, unless this is averted by a new planetary stewardship. This paper critically evaluates this chronology and finds (a) that there is insufficient evidence for an imminent irreversible tipping point, and (b) that the international community established a new planetary stewardship in 1992 when it agreed on new conventions on climate change and biodiversity in response to three decades of warnings about global environmental problems. The paper proposes an alternative framework for conceptualizing the transition between Stages 2 and 3 of the Anthropocene. This generates the hypothesis that after the actual carbon dioxide concentration of the atmosphere has exceeded a critical threshold level, some biophysical processes will change at rates proportional to the difference between the carbon dioxide concentration of the atmosphere and the threshold level, and to the rate of climate change. Evidence is presented which suggests that this new reversible tipping point could have been passed before 1980, when enhanced forest growth was first observed in mature forests in Amazonia. Modelling simulations suggest that this temporal relativity effect could soon be joined by a spatio-temporal relativity effect, as species become committed to extinction and/or form new species assemblages in the 21st Century when climate zones shift. Since this new tipping point is reversible there is still time for planetary stewardship to become more effective and minimize the harmful effects of climate change
Citizen Observatories and the New Earth Observation Science
Earth observation is diversifying, and now includes new types of systems, such as citizen observatories, unmanned aerial vehicles and wireless sensor networks. However, the Copernicus Programme vision of a seamless chain from satellite data to usable information in the hands of decision makers is still largely unrealized, and remote sensing science lacks a conceptual framework to explain why. This paper reviews the literatures on citizen science, citizen observatories and conceptualization of remote sensing systems. It then proposes a Conceptual Framework for Earth Observation which can be used in a new Earth observation science to explain blockages in the chain from collecting data to disseminating information in any Earth observation system, including remote sensing systems. The framework differs from its predecessors by including social variables as well as technological and natural ones. It is used here, with evidence from successful citizen science projects, to compare the factors that are likely to influence the effectiveness of satellite remote sensing systems and citizen observatories. The paper finds that constraints on achieving the seamless āCopernicus Chainā are not solely technical, as assumed in the new Space Strategy for Europe, but include social constraints too. Achieving the Copernicus Chain will depend on the balance between: (a) the āforwardā momentum generated by the repetitive functioning of each component in the system, as a result of automatic operation or human institutions, and by the efficiency of interfaces between components; and (b) the ābackwardā flow of information on the information needs of end users. Citizen observatories will face challenges in components which for satellite remote sensing systems are: (a) automatic or straightforward, e.g., sensor design and launch, data collection, and data products; and (b) also challenging, e.g., data processing. Since citizen observatories will rely even more on human institutions than remote sensing systems to achieve repetitive functioning, one of their greatest strengthsāusing a ācrowdā of hand-held sensors to cover large areasācould also be one of their greatest weaknesses
Recommended from our members
Numerical Simulation of Baroclinic Jovian Vortices
We examine the evolution of baroclinic vortices in a time-dependent, nonlinear numerical model of a Jovian atmosphere. The model uses a normal-mode expansion in the vertical, using the barotropic and first two baroclinic modes. Results for the stability of baroclinic vortices on an f plane in the absence of a mean zonal flow are similar to results of Earth vortex models, although the presence of a fluid interior on the Jovian planets shifts the stability boundaries to smaller length scales. The presence of a barotropic mean zonal flow in the interior stabilizes vortices against instability and significantly modifies the finite amplitude form of baroclinic instabilities. The effect of a zonal flow on a form of barotropic instability produces periodic oscillations in the latitude and longitude of the vortex as observed at the level of the cloud tops. This instability may explain some, but not all, observations of longitudinal oscillations of vortices on the outer planets. Oscillations in aspect ratio and orientation of stable vortices in a zonal shear flow are observed in this baroclinic model, as in simpler twodimensional models. Such oscillations are also observed in the atmospheres of Jupiter and Neptune. The meridional propagation and decay of vortices on a Ī² plane is inhibited by the presence of a mean zonal flow. The direction of propagation of a vortex relative to the mean zonal flow depends upon the sign of the meridional potential vorticity gradient; combined with observations of vortex drift rates, this may provide a constraint on model assumption for the flow in the deep interior of the Jovian planets
A Study to Determine if At Risk Adults are Adequately Trained to Perform Well and Secure a Job After Utilizing the Norfolk Skills Center Horticulture Program
The purpose of this study was to answer the following questions: 1. Did the adult get hired in horticulture? 2. Was the job an entry level position or did the adult enter at a higher level? 3. How well did the N.S.C. horticulture program equip the adult for their job? 4. What modifications should be made within the curriculum, new equipment, and/or other recommendations
Some implications of sampling choices on comparisons between satellite and model aerosol optical depth fields
The comparison of satellite and model aerosol optical depth (AOD) fields provides useful information on the strengths and weaknesses of both. However, the sampling of satellite and models is very different and some subjective decisions about data selection and aggregation must be made in order to perform such comparisons. This work examines some implications of these decisions, using GlobAerosol AOD retrievals at 550 nm from Advanced Along-Track Scanning Radiometer (AATSR) measurements, and aerosol fields from the GEOS-Chem chemistry transport model. It is recommended to sample the model only where the satellite flies over on a particular day; neglecting this can cause regional differences in model AOD of up to 0.1 on monthly and annual timescales. The comparison is observed to depend strongly upon thresholds for sparsity of satellite retrievals in the model grid cells. Requiring at least 25% coverage of the model grid cell by satellite data decreases the observed difference between the two by approximately half over land. The impact over ocean is smaller. In both model and satellite datasets, there is an anticorrelation between the proportion <i>p</i> of a model grid cell covered by satellite retrievals and the AOD. This is attributed to small <i>p</i> typically occuring due to high cloud cover and lower AODs being found in large clear-sky regions. Daily median AATSR AODs were found to be closer to GEOS-Chem AODs than daily means (with the root mean squared difference being approximately 0.05 smaller). This is due to the decreased sensitivity of medians to outliers such as cloud-contaminated retrievals, or aerosol point sources not included in the model
The effect of a scanning flat fold mirror on a CMB B-mode experiment
We investigate the possibility of using a flat-fold beam steering mirror for
a CMB B-mode experiment. An aluminium flat-fold mirror is found to add
0.075% polarization, which varies in a scan synchronous way. Time-domain
simulations of a realistic scanning pattern are performed, and the effect on
the power-spectrum illustrated and a possible method of correction applied.Comment: 8 pages, 5 figures. Accepted for publication in Rev Sci Ins
Extensive differential protein phosphorylation as intraerythrocytic Plasmodium falciparumschizonts develop into extracellular invasive merozoites
Pathology of the most lethal form of malaria is caused by Plasmodium falciparum asexual blood stages and initiated by merozoite invasion of erythrocytes. We present a phosphoproteome analysis of extracellular merozoites revealing 1765 unique phosphorylation sites including 785 sites not previously detected in schizonts. All MS data have been deposited in the ProteomeXchange with identifier PXD001684 (http://proteomecentral.proteomexchange.org/dataset/PXD001684). The observed differential phosphorylation between extra and intraerythrocytic life-cycle stages was confirmed using both phospho-site and phospho-motif specific antibodies and is consistent with the core motif [K/R]xx[pS/pT] being highly represented in merozoite phosphoproteins. Comparative bioinformatic analyses highlighted protein sets and pathways with established roles in invasion. Within the merozoite phosphoprotein interaction network a subnetwork of 119 proteins with potential roles in cellular movement and invasion was identified and suggested that it is coregulated by a further small subnetwork of protein kinase A (PKA), two calcium-dependent protein kinases (CDPKs), a phosphatidyl inositol kinase (PI3K), and a GCN2-like elF2-kinase with a predicted role in translational arrest and associated changes in the ubquitinome. To test this notion experimentally, we examined the overall ubiquitination level in intracellular schizonts versus extracellular merozoites and found it highly upregulated in merozoites. We propose that alterations in the phosphoproteome and ubiquitinome reflect a starvation-induced translational arrest as intracellular schizonts transform into extracellular merozoites
Reducing Global Environmental Uncertainties in Reports of Tropical Forest Carbon Fluxes to REDD+ and the Paris Agreement Global Stocktake
The magnitude of net carbon dioxide emissions resulting from global forest carbon change, and hence the contribution of forests to global climate change, is highly uncertain, owing to the lack of direct measurement by Earth observation and ground data collection. This paper uses a new method to evaluate this uncertainty with greater precision than before. Sources of uncertainty are divided into conceptualization and measurement categories and distributed between the spatial, vertical and temporal dimensions of Earth observation. The method is applied to Forest Reference Emission Level (FREL) reports and National Greenhouse Gas Inventories (NGGIs) submitted to the UN Framework Convention on Climate Change (UNFCCC) by 12 countries containing half of tropical forest area. The two sets of estimates are typical of those to be submitted to the Reducing Emissions from Deforestation and Degradation (REDD+) mechanism of the UNFCCC and the 2023 Global Stocktake of its Paris Agreement, respectively. Assembling the Uncertainty Fingerprint of each estimate shows that Uncertainty Scores are between 10 and 14 for the NGGIs and 5 and 10 for the FREL reports, and so both exceed the threshold of 2 when it is advisable to evaluate uncertainty by standard statistical methods. Conceptualization uncertainties account for 60% of all uncertainties in the NGGIs and 47% in the FREL reports, e.g., there is incomplete coverage of forest carbon fluxes, and limited disaggregation of fluxes between different ecosystem types and forest carbon pools. Of the measurement uncertainties, all FREL reports base forest area estimates on at least medium resolution satellite data, compared with only 3 NGGIs; after REDD+ Readiness schemes, mean area mapping frequency has fallen to 2.3 years in Latin America and 3.0 years in Asia, but only 8.3 years in Africa; and carbon density estimates are based on national forest inventory data in all FREL reports but only 4 NGGIs. The effectiveness of the Global Stocktake and REDD+ monitoring will therefore be constrained by considerable uncertainties, and to reduce these requires a new phase of REDD+ Readiness to ensure more frequent national forest inventories and forest carbon mapping
The malaria parasite cyclic GMP-dependent protein kinase plays a central role in blood-stage schizogony
A role for the Plasmodium falciparum cyclic GMP (cGMP)-dependent protein kinase (PfPKG) in gametogenesis in the malaria parasite was elucidated previously. In the present study we examined the role of PfPKG in the asexual blood-stage of the parasite life cycle, the stage that causes malaria pathology. A specific PKG inhibitor (compound 1, a trisubstituted pyrrole) prevented the progression of P. falciparum schizonts through to ring stages in erythrocyte invasion assays. Addition of compound 1 to ring-stage parasites allowed normal development up to 30 h postinvasion, and segmented schizonts were able to form. However, synchronized schizonts treated with compound 1 for ā„6 h became large and dysmorphic and were unable to rupture or liberate merozoites. To conclusively demonstrate that the effect of compound 1 on schizogony was due to its selective action on PfPKG, we utilized genetically manipulated P. falciparum parasites expressing a compound 1-insensitive PfPKG. The mutant parasites were able to complete schizogony in the presence of compound 1 but not in the presence of the broad-spectrum protein kinase inhibitor staurosporine. This shows that PfPKG is the primary target of compound 1 during schizogony and provides direct evidence of a role for PfPKG in this process. Discovery of essential roles for the P. falciparum PKG in both asexual and sexual development demonstrates that cGMP signaling is a key regulator of both of these crucial life cycle phases and defines this molecule as an exciting potential drug target for both therapeutic and transmission blocking action against malaria
- ā¦