Abstract: In Ethiopia, the demand for land for urbanisation is primarily met by converting rural land through expropriation. However, land expropriations are adversely affecting the previous land users by reducing the amount of production and their sources of income. In Bahir Dar, one of the fastest-growing cities in Ethiopia, approximately 300 landholdings are expropriated each year, on average, for urban expansion. This paper assesses the land expropriations to examine whether they offer economically appropriate compensation for the previous land users. Land expropriations for urbanisation between 2007/2008 and 2016/2017 were analysed based on data on land expropriation and its compensation payment obtained from the Bahir Dar City Land Administration and Management Office. Data were analysed using an exponential growth model and a stochastic budgeting technique in which Monte Carlo simulations are performed. Between 2007/2008 and 2016/2017, more than 1500 ha of land were included in the city's boundary through expropriation from 2900 landholders. The affected farmers received compensation that represents only 37 per cent of the value of current crop yields and its growth. The current compensation scheme ignores the impact of inflation on the prices of crops and assumes constant yields. It also excludes the value of crop residuals. We propose a workable discounted compensation framework that considers crop price and yield growths. This will make the compensation scheme more appropriate and make the affected farmers better off.

Abstract: This study investigates farmers' preferences and willingness to pay for cropland attributes in Bahir Dar, north-west Ethiopia. A choice experiment is used to elicit farmers' preferences between different land use attributes, including a monetary attribute. The study was conducted in the croplands that are threatened by land expro-priation for urban expansion. A survey was undertaken with 144 farmers in four rural kebeles surrounding the city (Addis Alem, Weramit, Wereb and Zenzelima). In the survey, respondents were provided with hypothetical land purchasing decisions, with three alternatives (i.e., two hypothetical parcels and an opt-out option). A choice experiment was undertaken to measure farmers' interest in different types of croplands, which varies with respect to irrigability, number of trees per ha, soil erosion resistance and water holding capacity of the cropland. Estimation of two mixed logit models was carried out. The estimation results show that, although the farmers did not show strong preferences for each attribute of the cropland, many farmers in the area showed interest in the proposed alternative croplands. Farmers show more interest for the land that is irrigable, gentle slope and with medium water holding capacity. The results also indicate that farmers assign highest marginal willingness to pay (MWTP) (79.01 ETB per square meter) for irrigated land, followed by medium water holding capacity with MWTP of 52.13 ETB per square meter. We believe that the results of this study would help land use policy and decision makers in the study area to consider the various attributes of cropland in land use planning, including land expropriation programs, which assures the sustainability of ecosystem services.

Abstract: The oxidation states of uranium in depleted uranium (DU) particles were determined by synchrotron radiation based mu-XANES, applied to individual particles isolated from selected samples collected at different sites in Kuwait. Based on scanning electron microscopy with X-ray microanalysis prior to mu-XANES, DU particles ranging from sub-microns to several hundred micrometers were observed. The.median particle size depended on sources and sampling sites; small-sized particles (median 13 mum) were identified in swipes taken from the inside of DU penetrators holes in tanks and in sandy soil collected below DU penetrators, while larger particles (median 44 mum) were associated with fire in a DU ammunition storage facility. Furthermore, the U-236/U-235 ratios obtained from accelerator mass spectrometry demonstrated that uranium in the DU particles originated from reprocessed fuel (about 10(-2) in DU from the ammunition facility, about 10(-3) for DU in swipes). Compared to well-defined standards, all investigated DU particles were oxidized. Uranium particles collected from swipes were characterized as UO2, U3O8 or a mixture of these oxidized forms, similar to that observed in DU affected areas in Kosovo. Uranium particles formed during fire in the DU ammunition facility were, however, present as oxidation state +5 and +6, with XANES spectra similar to solid uranyl standards. Environmental or health impact assessments for areas affected by DU munitions should therefore take into account the presence of respiratory UO2, U3O8 and even UO3 particles, their corresponding weathering rates and the subsequent mobilisation of U from oxidized DU particles. (C) 2004 Elsevier Ltd. All rights reserved.

Abstract: A combination of synchrotron radiation based X-ray microscopic techniques (ì-XRF, ì-XANES, ì-XRD) applied on single depleted uranium (DU) particles and semi-bulk leaching experiments has been employed to link the potential bioavailability of DU particles to site-specific particle characteristics. The oxidation states and crystallographic forms of U in DU particles have been determined for individual particles isolated from selected samples collected at different sites in Kosovo and Kuwait that were contaminated by DU ammunition during the 1999 Balkan conflict and the 1991 Gulf war. Furthermore, small soil or sand samples heavily contaminated with DU particles were subjected to simulated gastrointestinal fluid (0.16 M HCl) extractions. Characteristics of DU particles in Kosovo soils collected in 2000 and in Kuwait soils collected in 2002 varied significantly depending on the release scenario and to some extent on weathering conditions. Oxidized U (+6) was determined in large, fragile and bright yellow DU particles released during fire at a DU ammunition storage facility and crystalline phases such as schoepite (UO3·2.25H2O), dehydrated schoepite (UO3·0.75H2O) and metaschoepite (UO3·2.0H2O) were identified. As expected, these DU particles were rapidly dissolved in 0.16 M HCl (84 ± 3% extracted after 2 h) indicating a high degree of potential mobility and bioavailability. In contrast, the 2 h extraction of samples contaminated with DU particles originating either from corrosion of unspent DU penetrators or from impacted DU ammunition appeared to be much slower (2030%) as uranium was less oxidized (+4 to +6). Crystalline phases such as UO2, UC and metallic U or UTi alloy were determined in impacted DU particles from Kosovo and Kuwait, while the UO2,34 phase, only determined in particles from Kosovo, could reflect a more corrosive environment. Although the results are based on a limited number of DU particles, they indicate that the structure and extractability of DU particles released from similar sources (metallic U penetrators) will depend on the release scenarios (fire, impact) and to some extent environmental conditions. However, most of the DU particles (7396%) in all investigated samples were dissolved in 0.16 M HCl after one week indicating that a majority of the DU material is bioaccessible.

Abstract: We introduce single-shot x-ray tomography that aims to estimate the target image from a single cone-beam projection measurement. This linear inverse problem is extremely under-determined since the measurements are far fewer than the number of unknowns. Moreover, it is more challenging than conventional tomography, where a sufficiently large number of projection angles forms the measurements, allowing for a simple inversion process. However, single-shot tomography becomes less severe if the target image is only composed of known shapes. This paper restricts analysis to target image function that can be decomposed into known compactly supported non-negative-valued functions termed shapes. Hence, the shape prior transforms a linear ill-posed image estimation problem to a non-linear problem of estimating the roto-translations of the shapes. We circumvent the non-linearity by using a dictionary of possible roto-translations of the shapes. We propose a convex program CoShaRP, to recover the dictionary coefficients successfully. CoShaRP relies on simplex-type constraints and can be solved quickly using a primal-dual algorithm. The numerical experiments show that CoShaRP recovers shape stably from moderately noisy measurements.

Abstract: Purple non-sulphur bacteria (PNSB) are an emerging group of microbes attractive for applied microbiology applications such as wastewater treatment, plant biostimulants, microbial protein, polyhydroxyalkanoates and H-2 production. These photoorganoheterotrophic microbes have the unique ability to grow selectively on organic carbon in anaerobic photobioreactors. This so-called selectivity implies that the microbial community will have a low diversity and a high abundance of a particular PNSB species. Recently, it has been shown that certain PNSB strains can produce antimicrobials, yet it remains unclear whether these contribute to competitive inhibition. This research aimed to understand which type of antimicrobial PNSB produce and identify whether these compounds contribute to their selective growth. Mining 166 publicly-available PNSB genomes using the computational tool BAGEL showed that 59% contained antimicrobial encoding regions, more specifically biosynthetic clusters of bacteriocins and non-ribosomal peptide synthetases. Inter- and intra-species inhibition was observed in agar spot assays for Rhodobacter blasticus EBR2 and Rhodopseudomonas palustris EBE1 with inhibition zones of, respectively, 5.1 and 1.5-5.7 mm. Peptidomic analysis detected a peptide fragment in the supernatant (SVLQLLR) that had a 100% percentage identity match with a known non-ribosomal peptide synthetase with antimicrobial activity.

Abstract: In this tutorial review paper, we illustrate how computer modeling can contribute to a better insight in inductively coupled plasma-mass spectrometry (ICP-MS). We start with a brief overview on previous efforts, studying the fundamentals of the ICP and ICP-MS, with main focus on previous modeling activities. Subsequently, we explain in detail the model that we developed in previous years, and we show typical calculation results, illustrating the plasma characteristics, gas flow patterns and the sample transport, evaporation and ionization. We also present the effect of various experimental parameters, such as operating conditions, geometrical aspects and sample characteristics, to illustrate how modeling can help to elucidate the optimal conditions for improved analytical performance.

Abstract: The laser ablation-induced plasma was used as a composition-con trolled source for ion implantation in Si crystals. Then, laser ablation in combination with inductively coupled plasma mass spectrometry was used for the elemental depth profiling of the implanted samples. Monte Carlo simulations permitted us to conclude that a depth resolution of tens of nm would be necessary to define the shape of the implantation profiles, as is obtained using XPS and RBS, whereas a hundred nm depth resolution is sufficient to determine the total implanted dose. The detection power of LA-ICP-MS would routinely allow rapid analytical control on the trace level implanted dose. Nevertheless, this technique is limited in terms of depth profiling resolution due to pulse mixing and signal tailing induced during the aerosol transport. Raw signal processing procedures were developed for the minimization of shapeline dispersion, deconvolution of pulse mixing and more appropriate assessment of the implanted profiles. Shapeline dispersion could be corrected for by determining the signal waning constant and implementing this information for a non-affine alibi transformation of the LA-ICP-MS signal traces. Pulse mixing deconvolution was attained with an algorithm that considered accumulated signal intensity due to pulse-on-pulse stacking, i.e., the latest pulse on top of all antecedent individual pulses' exponential tails proportionally.

Abstract: Scanning macro-X-ray fluorescence analysis (MA-XRF) is rapidly being established as a technique for the investigation of historical paintings. The elemental distribution images acquired by this method allow for the visualization of hidden paint layers and thus provide insight into the artist's creative process and the painting's conservation history. Due to the lack of a dedicated, commercially available instrument the application of the technique was limited to a few groups that constructed their own instruments. We present the first commercially available XRF scanner for paintings, consisting of an X-ray tube mounted with a Silicon-Drift (SD) detector on a motorized stage to be moved in front of a painting. The scanner is capable of imaging the distribution of the main constituents of surface and sub-surface paint layers in an area of 80 by 60 square centimeters with dwell times below 10 ms and a lateral resolution below 100 mu m. The scanner features for a broad range of elements between Ti (Z = 22) and Mo (Z = 42) a count rate of more than 1000 counts per second (cps)?mass percent and detection limits of 100 ppm for measurements of 1 s duration. Next to a presentation of spectrometric figures of merit, the value of the technique is illustrated through a case study of a painting by Rembrandt's student Govert Flinck (1615-1660).

Abstract: A combined Raman and electrochemical study of natural orpiment (As2S3), an arsenic sulfide pigment, was used to assess the quick formation of oxidized species such as arsenic oxide (As2O3) upon exposing the pigment to 405 nm or 532 nm monochromatic light while simultaneously recording the Raman spectra of the exposed sample. During this process, a distortion of the main band at 355 cm−1, associated with the stretching of the AsS3/2 pyramids of natural orpiment, was observed as well as an increased intensity of the 359 cm−1 band, corresponding to covalent AsAs bonds in natural orpiment. The distortion was accompanied by an overall decrease of the global Raman signal for natural orpiment, which could be explained by a loss in the crystal structure. The same phenomena were recorded in reference natural orpiment model paint samples stored for a long time together with verdigris (Cu(OH)2·(CH3COO)2·5H2O) and minium (Pb3O4) paints, the latter two appearing darkened on their sides closest to the orpiment sample as well as in several historical samples containing natural orpiment mixed with various blue pigments. By SEM-EDX and XRPD analysis, respectively on loose material and cast thin-sections of model paint samples, the darkening was identified as dark sulfide species such as chalcocite (Cu2S) and galena (PbS), suggesting the release of volatile sulfide or related species by the natural orpiment paint. XANES analyses of paint samples presenting AsAs bond increase indicated the presence of sulfur species most likely identified as organosulfur compounds formed upon the AsAs bond formation and explained the darkening of the Cu- and Pb-based pigments. To the best of our knowledge, this article reports for the first time the light-induced formation of AsAs bonds in natural orpiment used as an artists' pigment and objectively demonstrates the incompatibility between orpiment and (arsenic) sulfide-sensitive pigments.

Abstract: A combination of synchrotron radiation (SR) micro X-ray fluorescence (m-XRF) and XRF mode X-ray absorption near edge structure (XANES) measurements at the Cr K-edge already allowed us to establish that the photo-reduction of chromates to Cr(III) compounds is the cause of darkening of chrome yellow pigments (PbCr1-xSxO4, 0 <= x <= 0.8) in a number of paintings by Vincent van Gogh and in corresponding artificially aged paint models. A silicon drift detector (SDD) was employed to record the Cr-K XRF radiation in these X-ray micro beam-based measurements. However, in view of the limited count rate capabilities and collection solid angle of a single device, m-XRF and m-XANES employing single element SDDs (or similar) are primarily suited for collection of spectral data from individual points. Additionally, collection of XRF maps via point-by-point scanning with relatively long dwell times per point is possible but is usually confined to small areas. The development of the 384 silicon-diode array Maia XRF detector has provided valuable solutions in terms of data acquisition rate, allowing for full spectral (FS) XANES imaging in XRF mode, i.e., where spectroscopic information is available at each pixel in the scanned map. In this paper, the possibilities of SR Cr K-edge FS-XANES imaging in XRF mode using the Maia detector are examined as a new data collection strategy to study the speciation and distribution of alteration products of lead chromate-based pigments in painting materials. The results collected from two micro-samples taken from two Van Gogh paintings and an aged paint model show the possibility to perform FS-XANES imaging in practical time frames (from several minutes to a few hours) by scanning regions of sample sizes of the same order (more than 500 mm). The sensitivity and capabilities of FS-XANES imaging in providing representative chemical speciation information at the microscale (spatial resolution from similar to 2 to 0.6 mm) over the entire scanned area are demonstrated by the identification of Cr(OH) 3, Cr(III) sulfates and/or Cr(III) organometallic compounds in the corresponding phase maps, as alteration products. Comparable Cr-speciation results were obtained by performing equivalent higher spatial resolution SR m-XRF/single-point m-XANES analysis using a more conventional SDD from smaller regions of interest of each sample. Thus, large-area XRF mode FS-XANES imaging (Maia detector) is here proposed as a valuable and complementary data collection strategy in relation to “ zoomed-in” high-resolution m-XRF mapping and single-point m-XANES analysis (SDD).

Abstract: Scientific analyses of ancient glasses have been carried out for many years using elemental chemical analysis. However, it is known that the control of the redox conditions in the glass melt has a strong implication on the final hue of glass because it affects Fe2+/SFe. Therefore an increasing number of studies on the redox conditions have been published in recent years by means of synchrotron based Xray absorption spectroscopy. This is a technique which is not easily accessible and requires dedicated facilities. In this paper we describe an alternative approach by means of optical absorption spectroscopy. We synthesised 10 soda-lime-silica glasses with known redox conditions and iron concentration to calibrate the absorption at 1100 nm as a function of Fe2+ concentration. The linear extinction coefficient was also determined. These glasses were also studied by means of X-ray Absorption Near Edge Structure (XANES) spectroscopy. Electron paramagnetic resonance spectroscopy was additionally used as an ancillary method to verify the quality of our data. Furthermore 28 samples from real archaeological samples were analysed by XANES and optical spectroscopy as a case study. The Fe2+/SFe values obtained were compared and demonstrated that the two techniques were in good agreement with each other. Optical spectroscopy can be applied in situ with moderate sample preparation to determine the concentration of Fe2+. To investigate the redox conditions, especially as a first screening approach, this methodology is an important tool to take into consideration before applying more sophisticated techniques such as XANES, which is more elaborate and requires high-tech resources.