Uncertainty on coastal flood risk calculations, and how to deal with it in coastal management: case of the Belgian coastal zone

A coastal flood risk calculation estimates the damage by coastal flooding for a certain time horizon. Fivedifferent sources of uncertainty can be distinguished: unpredictability of the weather; uncertainty on theextreme value probability distribution of storm surges; unknown future values of economic growth rate,population growth rate, sea level rise rate and discount rate; limited knowledge of the behaviour of thecoastal system; limited amount of measurements about the state of the coastal system. From a preliminaryanalysis for the Belgian coastal zone it is clear that the combined effect of these different sources ofuncertainty results in a very large uncertainty on the calculated risk, namely a sigma of a factor more than10. Some important sources of uncertainty are impossible to decrease substantially by doing research ormeasurements. Therefore the only option for coastal management is to deal with these large uncertainties.It is suggested to use calculation results relatively, namely to compare scenarios of coastal management inorder to determine which scenario can best use an available budget for investment. Also it is concludedthat risk calculation results would best be compared as ratios between scenarios (in %), not as differences(in euro/year)

Nodular lymphocyte predominant hodgkin lymphoma and T cell/histiocyte rich large B cell lymphoma : endpoints of a spectrum of one disease?

In contrast to the commonly indolent clinical behavior of nodular lymphocyte predominant Hodgkin lymphoma (NLPHL), T cell/histiocyte rich large B cell lymphoma (THRLBCL) is frequently diagnosed in advanced clinical stages and has a poor prognosis. Besides the different clinical presentations of these lymphoma entities, there are variants of NLPHL with considerable histopathologic overlap compared to THRLBCL. Especially THRLBCL-like NLPHL, a diffuse form of NLPHL, often presents a histopathologic pattern similar to THRLBCL, suggesting a close relationship between both lymphoma entities. To corroborate this hypothesis, we performed gene expression profiling of microdissected tumor cells of NLPHL, THRLBCL-like NLPHL and THRLBCL. In unsupervised analyses, the lymphomas did not cluster according to their entity. Moreover, even in supervised analyses, very few consistently differentially expressed transcripts were found, and for these genes the extent of differential expression was only moderate. Hence, there are no clear and consistent differences in the gene expression of the tumor cells of NLPHL, THRLBCL-like NLPHL and THRLBCL. Based on the gene expression studies, we identified BAT3/BAG6, HIGD1A, and FAT10/UBD as immunohistochemical markers expressed in the tumor cells of all three lymphomas. Characterization of the tumor microenvironment for infiltrating T cells and histiocytes revealed significant differences in the cellular composition between typical NLPHL and THRLBCL cases. However, THRLBCL-like NLPHL presented a histopathologic pattern more related to THRLBCL than NLPHL. In conclusion, NLPHL and THRLBCL may represent a spectrum of the same disease. The different clinical behavior of these lymphomas may be strongly influenced by differences in the lymphoma microenvironment, possibly related to the immune status of the patient at the timepoint of diagnosis

Analysis of N- and K-Ras Mutations in the Distinctive Tumor Progression Phases of Melanoma

Mutations in the ras genes are key events in the process of carcinogenesis; in particular, point mutations in codon 61 of exon 2 of the N-ras gene occur frequently in cutaneous melanoma. To investigate whether these mutations occur in early or late tumor progression phases, we searched for point mutations in the N- and K-ras genes in 69 primary cutaneous melanoma, 35 metastases, and seven nevocellular nevi in association with cutaneous melanoma. Lesions were microdissected in order to procure pure tumor samples from the distinctive growth phases of the cutaneous melanoma; the very sensitive denaturing gradient gel electrophoresis technique was used to visualize the mutations, and was followed by sequencing. Point mutations in the N-ras gene but not in the K-ras gene were detected on denaturing gradient gel electrophoresis. Twenty-three primary (33%) and nine metastatic (26%) melanomas showed bandshifts for N-ras. In the majority of cases, mutations occurring in early growth phases (i.e., the “intraepidermal” radial growth phase), were preserved in later growth phases (i.e., the invasive radial growth phase, vertical growth phase, and metastatic phase), which proves the clonal relationship between the successive growth phases. In three cases, however, the mutations differed between the distinctive growth phases within the same cutaneous melanoma, due to the occurrence of an additional mutation (especially in codon 61) in a later tumor progression phase. Our approach also permitted us to analyze the mutational status of nevi, associated with cutaneous melanoma. Six out of seven associated nevi carried the same sequence (mutated or wild-type) as the primary cutaneous melanoma, whereas in one case the sequence for N-ras differed between the primary melanoma and the associated nevus. In conclusion, this approach allowed us to demonstrate the clonal relationship between subsequent growth phases of melanoma and associated nevi; our results suggest that N-ras exon 1 mutations preferentially occur during early stages of tumor progression and hence may be involved in melanoma initiation, whereas those in N-ras exon 2 are found preferentially during later stages and hence are more probably involved in metastatic spread of cutaneous melanoma

Auto-Ubiquitination-Induced Degradation of MALT1-API2 Prevents BCL10 Destabilization in t(11;18)(q21;q21)-Positive MALT Lymphoma

BACKGROUND: The translocation t(11;18)(q21;q21) is the most frequent chromosomal aberration associated with MALT lymphoma and results in constitutive NF-kappaB activity via the expression of an API2-MALT1 fusion protein. The properties of the reciprocal MALT1-API2 were never investigated as it was reported to be rarely transcribed. PRINCIPAL FINDINGS: Our data indicate the presence of MALT1-API2 transcripts in the majority of t(11;18)(q21;q21)-positive MALT lymphomas. Based on the breakpoints in the MALT1 and API2 gene, the MALT1-API2 protein contains the death domain and one or both immunoglobulin-like domains of MALT1 (approximately 90% of cases)--mediating the possible interaction with BCL10--fused to the RING domain of API2. Here we show that this RING domain enables MALT1-API2 to function as an E3 ubiquitin ligase for BCL10, inducing its ubiquitination and proteasomal degradation in vitro. Expression of MALT1-API2 transcripts in t(11;18)(q21;q21)-positive MALT lymphomas was however not associated with a reduction of BCL10 protein levels. CONCLUSION: As we observed MALT1-API2 to be an efficient target of its own E3 ubiquitin ligase activity, our data suggest that this inherent instability of MALT1-API2 prevents its accumulation and renders a potential effect on MALT lymphoma development via destabilization of BCL10 unlikely

Resolving discharge parameters from atomic oxygen emission

A method is proposed to spatially resolve discharge parameters from experimental measurements of emission intensity and 1D numerical simulations including an O atom collisional-radiative model. The method can be used for different plasmas and conditions. Here, contracted microwave discharges for CO2 conversion are studied at intermediate to high pressures (100–300 mbar). Radial profiles of electron density (ne) are used as input in the model and corrected to successfully simulate the measured Gaussian profiles of emission intensity of the 777 nm transition (I777). As a result, radially-resolved parameters inaccessible in experiments, such as ne, power density (Pabs), electron temperature (Te), electric field and reaction rates, are numerically-obtained for several conditions. ne and Pabs approximately follow Gaussian profiles that are broader than that of I777. For pressures below 150 mbar, the difference in full width at half maximum is typically a factor 1.6. This consists in a phenomenon of optical contraction, which is due to concave profiles of O molar fraction and Te. The implications of the simulated profiles on the study of plasmas for CO2 conversion are discussed and it is shown that these profiles allow to explain high reactor performances at low pressures

Implications of thermo-chemical instability on the contracted modes in CO2 microwave plasmas

Understanding and controlling contraction phenomena of plasmas in reactive flows is essential to optimize the discharge parameters for plasma processing applications such as fuel reforming and gas conversion. In this work, we describe the characteristic discharge modes in a CO2&nbsp;microwave plasma and assess the impact of wave coupling and thermal reactivity on the contraction dynamics. The plasma shape and gas temperature are obtained from the emission profile and the Doppler broadening of the 777 nm O(5S ←&nbsp;5P) oxygen triplet, respectively. Based on these observations, three distinct discharge modes are identified in the pressure range of 10 mbar to atmospheric pressure. We find that discharge contraction is suppressed by an absorption cut-off of the microwave field at the critical electron density, resulting in a homogeneous discharge mode below the critical transition pressure of 85 mbar. Further increase in the pressure leads to two contracted discharge modes, one emerging at a temperature of 3000 K to 4000 K and one at a temperature of 6000 K to 7000 K, which correspond to the thermal dissociation thresholds of CO2&nbsp;and CO respectively. The transition dynamics are explained by a thermo-chemical instability, which arises from the coupling of the thermal-ionization instability to heat transfer resulting from thermally driven endothermic CO2&nbsp;dissociation reactions. These results highlight the impact of thermal chemistry on the contraction dynamics of reactive molecular plasmas.</p

CO2 Conversion in Nonuniform Discharges: Disentangling Dissociation and Recombination Mechanisms

Motivated by environmental applications such as synthetic fuel synthesis, plasma-driven conversion shows promise for efficient and scalable gas conversion of CO2 to CO. Both discharge contraction and turbulent transport have a significant impact on the plasma processing conditions, but are, nevertheless, poorly understood. This work combines experiments and modeling to investigate how these aspects influence the CO production and destruction mechanisms in the vortex-stabilized CO2 microwave plasma reactor. For this, a two-dimensional axisymmetric tubular chemical kinetics model of the reactor is developed, with careful consideration of the nonuniform nature of the plasma and the vortex-induced radial turbulent transport. Energy efficiency and conversion of the dissociation process show a good agreement with the numerical results over a broad pressure range from 80 to 600 mbar. The occurrence of an energy efficiency peak between 100 and 200 mbar is associated with a discharge mode transition. The net CO production rate is inhibited at low pressure by the plasma temperature, whereas recombination of CO to CO2 dominates at high pressure. Turbulence-induced cooling and dilution of plasma products limit the extent of the latter. The maxima in energy efficiency observed experimentally around 40% are related to limits imposed by production and recombination processes. Based on these insights, feasible approaches for optimization of the plasma dissociation process are discussed.</p

Characterization of the CO2 microwave plasma based on the phenomenon of skin-depth-limited contraction

The subatmospheric CO2 microwave plasma is known to contract to a narrow filament with rising pressure as result of a mode transition. This changing state of contraction is investigated in relation to its dielectric properties, in order to directly relate the discharge parameters to the discharge radius. The electron density and gas temperature are measured, respectively, by 168 GHz microwave interferometry and Doppler broadening of the 777 nm oxygen emission lines. The plasma is operated in steady state with 1400 W at 2.45 GHz, between 100 mbar and 400 mbar. Electron density values in the central region range from 1018 to 1020 m−3 between the discharge modes, while the gas temperature increases from 3000 K to 6500 K, in good agreement with previously reported values. Based on the dielectric properties of the discharge in relation to the plasma radius, it is found that the discharge column constitutes a radius of a single skin depth. Implications of these insights on the conditions of previously reported CO2 dissociation experiments are discussed.</p

Numerical model for the determination of the reduced electric field in a CO2 microwave plasma derived by the principle of impedance matching

Three dimensional electromagnetic modelling of a free-standing CO2 microwave plasma has been performed, by describing the plasma as a dielectric medium. The relative permittivity and conductivity of the medium are parametrised. The waveguide geometry from experiment, including the tuner, is put into the model, knowing that this corresponds to maximum power transfer of the microwave generator to the plasma under plasma impedance matching conditions. Two CO2 plasma discharge regimes, differing mainly in pressure, input power and temperature, have been studied. The model\u27s validity has been checked through study of materials of known conductivity. From measurements of the neutral gas temperature and the plasma electron density profile, the reduced electric field is determined. From the parametrisation of the dielectric properties, a range for the effective electron-neutral collision frequency for momentum transfer is estimated. The results for the reduced electric field and the range of the electron neutral collision frequency obtained, are consistent as verified by simulations using BOLSIG+. In addition, from this comparison it is possible to narrow down the range of the collision frequencies, and to estimate the electron temperature. The reduced electric field lies between 80 and 180 Td for the relatively low pressure, low input power, the so-called \u27diffuse\u27 regime. For the relatively high pressure, high input power (\u27contracted\u27) regime it lies between 10 and 60 Td. The normalised collision frequency lies between 1.6 and 2.3 for the diffuse regime, while for the contracted regime it lies between 2 and 3. The electron temperature ranges from 2 to 3 eV for the diffuse regime, and from 0.5 to 1 eV for the contracted regime. Related content: 10.1088/1361-6595/ab1ca1</p