Determination of the methane budget of the Amazon region utilizing airborne methane observations in combination with atmospheric transport and vegetation modeling

The Amazon basin is an important player in the global methane cycle. Objectives of this work are to establish a forward and inverse modelling framework on regional scale and to determine the methane budget in the Amazon region. Within the BARCA project (Balanço Atmosférico Regional de Carbono na Amazônia) to airborne measurement campaigns were conducted, one in November 2008 and one in May 2009. The analysis of the methane observations confirms that the Amazon basin is a strong source of methane. The majority of the emissions is found to have biogenic origin, i.e. from wetlands. A comparison of five global methane inversions shows the advantage of using satellite observations in inversion systems. The WRF (Weather Research and Forecasting) Greenhouse Gas model was developed to perform high-resolution simulations of the atmospheric methane distribution in the Amazon region. The newly written code is available within the official WRF-Chem version 3.4 release. Simulations for the two months of the BARCA campaigns with two different wetland models and three different wetland maps were conducted with the WRF Greenhouse Gas model. The comparison to observations indicates that the choice of the wetland map is more important than the choice of the wetland model for a comparison to aircraft observations. Flights with a good representation of the atmospheric transport in the model show a higher correlation between observations and simulations. The two-step regional inversion scheme TM3-STILT was applied to the Amazon region for the year 2009 using observations from the 35 m high TT34 tower. The inversion shows improvements in the representation of the seasonal cycle of the methane emissions in the Amazon basin. However, the determination of the methane budget in the Amazon basin is still highly uncertain.Das Amazonasgebiet ist eine bedeutende Methanquelle im globalen Methankreislauf. Gegenstand dieser Dissertation ist der Aufbau einer Modellinfrastruktur auf regionaler Skala sowie die Bestimmung des Methanbudgets im Amazonasgebiet. Innerhalb des BARCA Projektes (Balanço Atmosférico Regional de Carbono na Amazônia) wurden zwei Flugzeugmesskampagnen im Amazonasgebiet im November 2008 und im Mai 2009 durchgeführt. Die Analyse der Methandaten bestätigt, dass das Amazonasgebiet eine starke Methanquelle ist und der Großteil der Emissionen aus Feuchtgebieten (sogenannten „Wetlands“) stammt. Vergleiche mit fünf globalen Methaninversionen zeigen den Vorteil der Nutzung von Satellitendaten in Inversionssystemen. Das WRF (Weather Research and Forecasting) Greenhouse Gas Modell wurde entwickelt, um hoch aufgelöste Simulationen der atmosphärischen Methanverteilung im Amazonasgebiet durchführen zu können. Der Programmcode steht innerhalb der offiziellen WRF-Chem Version 3.4 zu wissenschaftlichen Zwecken frei zur Verfügung. Hiermit wurden für die beiden Monate der BARCA Flugzeugkampagnen Methansimulationen mit zwei verschiedenen Wetland-Modellen und drei verschiedenen Wetland-Karten durchgeführt. Der Vergleich mit den Beobachtungen zeigt, dass die richtige Wahl der Wetland-Karte für den Vergleich mit Flugzeugdaten entscheidender ist als die Wahl des Wetland-Modells. Flüge, bei denen das Atmosphärentransportmodell den konvektiven Transport in der Atmosphäre gut wiedergibt, zeigen eine höhere Korrelation von Beobachtungen und Simulationen. Das zweistufige regionale Inversionsschema TM3-STILT wurde für das Jahr 2009 für Methan unter Zuhilfenahme von TT34-Turmbeobachtungen in 35 m Höhe für das Amazonasgebiet angewendet. Die Inversion zeigte Verbesserungen bei der korrekten Wiedergabe des saisonalen Verlaufs der Methanemissionen im Amazonasgebiet. Insgesamt ist die Bestimmung des Methanbudgets im Amazonasgebiet immer noch mit sehr großen Unsicherheiten behaftet

Eigendamage: an Eigendeformation model for the variational approximation of cohesive fracture -- a one-dimensional case study

We study an approximation scheme for a variational theory of cohesive fracture in a one-dimensional setting. Here, the energy functional is approximated by a family of functionals depending on a small parameter $0 < \varepsilon \ll 1$ and on two fields: the elastic part of the displacement field and an eigendeformation field that describes the inelastic response of the material beyond the elastic regime. We measure the inelastic contributions of the latter in terms of a non-local energy functional. Our main result shows that, as $\varepsilon \to 0$, the approximate functionals $\Gamma$-converge to a cohesive zone model.Comment: Comments are welcome

A minimalist chemical model of matrix metalloproteinases- Can small peptides mimic the more rigid metal binding sites of proteins?

In order to develop a minimalist chemical model of matrix metalloproteinases (MMPs), we synthesized a pentadecapeptide (Ac-KAHEFGHSLGLDHSK-NH2) corresponding to the catalytic zinc(II) binding site of human MMP-13. The multi-domain structural organization of MMPs fundamentally determines their metal binding affinity, catalytic activity and selectivity. Our potentiometric, UV-VIS, CD, EPR, NMR, ESI-MS and kinetic study are aimed to explore the usefulness of flexible peptides to mimic the more rigid metal binding sites of proteins, to examine the intrinsic metal binding properties of this naked sequence, as well as to contribute the development of a minimalist, peptide-based chemical model of MMPs, including the catalytic properties. Since multiimidazole environment is also characteristic for copper(II), and recently copper(II) containing variants of MMPs have been identified, we also studied the copper(II) complexes of the above peptide. Around pH 6-7 the peptide, similarly to MMPs, offers {3Nim} coordinated binding site for both zinc(II) and copper(II). In the case of copper(II), the formation of amide coordinated species at higher pH ceased the analogy with the copper(II) containing MMP variant. On the other hand, the zinc(II)-peptide system mimics some basic features of the MMP active sites: the main species around pH 7 (ZnH2L) possesses {3Nim,H2O} coordination environment, the deprotonation of the zinc-bound water takes place near to the physiological pH, it forms relatively stable ternary complexes with hydroxamic acids, and the species ZnH2L(OH) and ZnH2L(OH)2 have notable hydrolytic activity between pH 7-9

Greenhouse gas observation network design for Africa

An optimal network design was carried out to prioritise the installation or refurbishment of greenhouse gas (GHG) monitoring stations around Africa. The network was optimised to reduce the uncertainty in emissions across three of the most important GHGs: CO2, CH4, and N2O. Optimal networks were derived using incremental optimisation of the percentage uncertainty reduction achieved by a Gaussian Bayesian atmospheric inversion. The solution for CO2 was driven by seasonality in net primary productivity. The solution for N2O was driven by activity in a small number of soil flux hotspots. The optimal solution for CH4 was consistent over different seasons. All solutions for CO2 and N2O placed sites in central Africa at places such as Kisangani, Kinshasa and Bunia (Democratic Republic of Congo), Dundo and Lubango (Angola), Zoétélé (Cameroon), Am Timan (Chad), and En Nahud (Sudan). Many of these sites appeared in the CH4 solutions, but with a few sites in southern Africa as well, such as Amersfoort (South Africa). The multi-species optimal network design solutions tended to have sites more evenly spread-out, but concentrated the placement of new tall-tower stations in Africa between 10ºN and 25ºS. The uncertainty reduction achieved by the multi-species network of twelve stations reached 47.8% for CO2, 34.3% for CH4, and 32.5% for N2O. The gains in uncertainty reduction diminished as stations were added to the solution, with an expected maximum of less than 60%. A reduction in the absolute uncertainty in African GHG emissions requires these additional measurement stations, as well as additional constraint from an integrated GHG observatory and a reduction in uncertainty in the prior biogenic fluxes in tropical Africa

Large emissions from floodplain trees close the Amazon methane budget

Wetlands are the largest global source of atmospheric methane (CH4), a potent greenhouse gas. However, methane emission inventories from the Amazon floodplain, the largest natural geographic source of CH4 in the tropics, consistently underestimate the atmospheric burden of CH4 determined via remote sensing and inversion modelling, pointing to a major gap in our understanding of the contribution of these ecosystems to CH4 emissions. Here we report CH4 fluxes from the stems of 2,357 individual Amazonian floodplain trees from 13 locations across the central Amazon basin. We find that escape of soil gas through wetland trees is the dominant source of regional CH4 emissions. Methane fluxes from Amazon tree stems were up to 200 times larger than emissions reported for temperate wet forests6 and tropical peat swamp forests, representing the largest non-ebullitive wetland fluxes observed. Emissions from trees had an average stable carbon isotope value (δ13C) of −66.2 ± 6.4 per mil, consistent with a soil biogenic origin. We estimate that floodplain trees emit 15.1 ± 1.8 to 21.2 ± 2.5 teragrams of CH4 a year, in addition to the 20.5 ± 5.3 teragrams a year emitted regionally from other sources. Furthermore, we provide a ‘top-down’ regional estimate of CH4 emissions of 42.7 ± 5.6 teragrams of CH4 a year for the Amazon basin, based on regular vertical lower-troposphere CH4 profiles covering the period 2010–2013. We find close agreement between our ‘top-down’ and combined ‘bottom-up’ estimates, indicating that large CH4 emissions from trees adapted to permanent or seasonal inundation can account for the emission source that is required to close the Amazon CH4 budget. Our findings demonstrate the importance of tree stem surfaces in mediating approximately half of all wetland CH4 emissions in the Amazon floodplain, a region that represents up to one-third of the global wetland CH4 source when trees are combined with other emission sources

Perspectives of healthcare professionals in England on falls interventions for people with dementia: a qualitative interview study

© 2019 Author(s) (or their employer(s)). Re-use permitted under CC BY-NC. Objective To explore the experiences of healthcare professionals working in falls prevention and memory assessment services in providing assessments and interventions for falls risk reduction in people with dementia. Design This is a qualitative study using 19 semistructured interviews. Interviews were analysed through thematic analysis. Setting Community-based falls and memory assessment services in the East Midlands, UK. Participants Nurses (n=10), physiotherapists (n=5), occupational therapists (n=3) and a psychiatrist (n=1). Results Three substantive themes were identified: challenges posed by dementia, adaptations to make falls prevention appropriate for people with dementia and organisational barriers. Patients' poor recall, planning and increased behavioural risk associated with dementia were key problems. Healthcare professionals provided many suggestions on how to overcome these challenges, such as adapting exercise interventions by using more visual aids. Problems associated with cognitive impairment created a need for additional support, for instance longer interventions, and supervision by support workers, to enable effective intervention, yet limited resources meant this was not always achievable. Communication between mental and physical health teams could be ineffective, as services were organised as separate entities, creating a reliance on third parties to be intermediaries. Structural and organisational factors made it difficult to deliver optimal falls prevention for people living with dementia. Conclusions Healthcare professionals experience challenges in providing falls prevention to people with dementia at the individual and organisational levels. Interventions can be adapted for people with dementia, but this requires additional resources and improved integration of services. Future research is needed to develop and test the effectiveness and cost-effectiveness of such services

A New Heterobinuclear FeIIICuII Complex with a Single Terminal FeIII–O(phenolate) Bond. Relevance to Purple Acid Phosphatases and Nucleases

A novel heterobinuclear mixed valence complex [Fe^IIICu^II(BPBPMP)(OAc)_2]ClO_4, 1, with the unsymmetrical N_5O_2 donor ligand 2-bis[{(2-pyridylmethyl)aminomethyl}-6-{(2-hydroxybenzyl)(2-pyridylmethyl)} aminomethyl]-4-methylphenol (H_2BPBPMP) has been synthesized and characterized. A combination of data from mass spectrometry, potentiometric titrations, X-ray absorption and electron paramagnetic resonance spectroscopy, as well as kinetics measurements indicates that in ethanol/water solutions an [Fe^III-(nu)OH-Cu^IIOH_2]+ species is generated which is the likely catalyst for 2,4-bis(dinitrophenyl)phosphate and DNA hydrolysis. Insofar as the data are consistent with the presence of an Fe_III-bound hydroxide acting as a nucleophile during catalysis, 1 presents a suitable mimic for the hydrolytic enzyme purple acid phosphatase. Notably, 1 is significantly more reactive than its isostructural homologues with different metal composition (Fe^IIIM^II, where M^II is Zn^II, Mn^II, Ni^II,or Fe^II). Of particular interest is the observation that cleavage of double-stranded plasmid DNA occurs even at very low concentrations of 1 (2.5 nuM), under physiological conditions (optimum pH of 7.0), with a rate enhancement of 2.7 x 10^7 over the uncatalyzed reaction. Thus, 1 is one of the most effective model complexes to date, mimicking the function of nucleases

Heterozygous Loss-of-Function SEC61A1 Mutations Cause Autosomal-Dominant Tubulo-Interstitial and Glomerulocystic Kidney Disease with Anemia

Autosomal-dominant tubulo-interstitial kidney disease (ADTKD) encompasses a group of disorders characterized by renal tubular and interstitial abnormalities, leading to slow progressive loss of kidney function requiring dialysis and kidney transplantation. Mutations in UMOD, MUC1, and REN are responsible for many, but not all, cases of ADTKD. We report on two families with ADTKD and congenital anemia accompanied by either intrauterine growth retardation or neutropenia. Ultrasound and kidney biopsy revealed small dysplastic kidneys with cysts and tubular atrophy with secondary glomerular sclerosis, respectively. Exclusion of known ADTKD genes coupled with linkage analysis, whole-exome sequencing, and targeted re-sequencing identified heterozygous missense variants in SEC61A1—c.553A>G (p.Thr185Ala) and c.200T>G (p.Val67Gly)—both affecting functionally important and conserved residues in SEC61. Both transiently expressed SEC6A1A variants are delocalized to the Golgi, a finding confirmed in a renal biopsy from an affected individual. Suppression or CRISPR-mediated deletions of sec61al2 in zebrafish embryos induced convolution defects of the pronephric tubules but not the pronephric ducts, consistent with the tubular atrophy observed in the affected individuals. Human mRNA encoding either of the two pathogenic alleles failed to rescue this phenotype as opposed to a complete rescue by human wild-type mRNA. Taken together, these findings provide a mechanism by which mutations in SEC61A1 lead to an autosomal-dominant syndromic form of progressive chronic kidney disease. We highlight protein translocation defects across the endoplasmic reticulum membrane, the principal role of the SEC61 complex, as a contributory pathogenic mechanism for ADTKD