How policy changes affected cocoa sectors in sub-Saharan African countries

Structural adjustment programs in sub-Saharan African countries in the 1980s removed trade restrictions, price controls, and export taxes and abolished state-owned commodity marketing bodies. The authors studied the effects of these policy changes on the coca sector, using a global econometric model specifying major producer countries through the vintage-capital approach. They focused on Ghana and Nigeria (major cocoa producers that undertook structural adjustment programs), as well as on Cote d'Ivoire and Cameroon. The impact on world cocoa prices of structural adjustment programs in Ghana and Nigeria was relatively small. The results imply that, without structural adjustment programs in Ghana and Nigeria, world cocoa prices in the late 1980s would have been about US$1,060/ton (in 1985 constant dollars), instead of US$850/ton. So, without the structural adjustment programs, 1989-90 world prices in real terms would have been about 45 percent lower than they were in the early 1980s, compared with an actual decline of 55 percent. Much more important in depressing prices in this period was the rapid increase in production in Brazil, Cote d'Ivoire, Indonesia, and Malaysia (which together accounted for about 75 percent of the increased production in that decade). That increased production resulted largely from tree planting in response to higher world cocoa prices in the late 1970s -- and subsequent increases in productivity. The results of counterfactual simulations suggest that cocoa production in Ghana would have been at almost half its 1989-90 level if Ghana had not implemented its structural adjustment program. The producers'surplus would have been lower without the program, and the government's budget deficit would have been unsustainable. The effects of the structural adjustment program in Nigeria are mixed. The simulation results show lower cocoa production but higher government revenue without the reforms. But the program was evaluated only three years after the reforms, so the full effects on production had not been realized. The structural adjustment programs in Ghana and Nigeria had a negative effect on other cocoa-producing countries in sub-Saharan Africa and the rest of the world -- producing an estimated loss (in government revenue from cocoa exports and producer surplus) of about 15 percent in other sub-Saharan African countries. Results show that both Cote d'Ivoire and Cameroon would have been better off had they set export taxes at a higher level (closer to an estimated"optimal"level) at the same time that they depreciated the real exchange rate. Producer prices could have been sustained at their earlier higher level, or even raised, without hurting government revenues. Structural adjustment programs in Ghana and Nigeria had a negative effect on producers in other countries, but not adopting such policies would have been economically irrational, contend the authors.Environmental Economics&Policies,Economic Theory&Research,Economic Stabilization,Access to Markets,Markets and Market Access

Industrial grade 2D Molybdenum Disulphide (MoS2): An in-vitro exploration of the impact on cellular uptake, cytotoxicity, and inflammation

The recent surge in graphene research, since its liquid phase monolayer isolation and characterization in 2004, has led to advancements which are accelerating the exploration of alternative 2D materials such as molybdenum disulphide (MoS2), whose unique physico-chemical properties can be exploited in applications ranging from cutting edge electronic devices to nanomedicine. However, to assess any potential impact on human health and the environment, the need to understand the bio-interaction of MoS2 at a cellular and sub-cellular level is critical. Notably, it is important to assess such potential impacts of materials which are produced by large scale production techniques, rather than research grade materials. The aim of this study was to explore cytotoxicity, cellular uptake and inflammatory responses in established cell-lines that mimic different potential exposure routes (inhalation, A549; ingestion, AGS; monocyte, THP-1) following incubation with MoS2 flakes of varying sizes (50 nm, 117 nm and 177 nm), produced by liquid phase exfoliation. Using high content screening (HCS) and live/dead assays, it was established that 1 μg/ml (for the three different MoS2 sizes) did not induce toxic effects on any of the cell-lines. Confocal microscopy images revealed a normal cellular morphology in all cases. Transmission electron microscopy (TEM) confirmed the uptake of all MoS2 nanomaterials in all the cell-lines, the MoS2 ultimately locating in single membrane vesicles. At such sub-lethal doses, inflammatory responses are observed, however, associated, at least partially, with the presence of lipopolysaccharide endotoxin in nanomaterial suspensions and surfactant samples. Therefore, the inflammatory response of the cells to the MoS2 or endotoxin contamination was interrogated using a 10-plex ELISA which illustrates cytokine production. The experiments carried out using wild-type and endotoxin hyporesponsive bone marrow derived dendritic cells confirmed that the inflammatory responses result from a combination of endotoxin contamination, the MoS2 nanomaterials themselves, and the stabilizing surfactant

Label-free Screening of Biochemical Changes in Macrophage-like Cells Following MoS2 Exposure Using Raman Micro-spectroscopy

The emergence of large scale production techniques for 2D particulate materials has dramatically increased their applications potential. Understanding the interactions of biological cells with such particulate material is therefore of paramount importance, both for toxicological assessment and potential biomedical applications. Conventional in-vitro cytological assays commonly record only a single colorimetric end-point, and do not provide an in-depth analysis of how such materials are uptaken and processed within cells. To demonstrate its potential as an alternative, label free approach, confocal Raman micro-spectroscopy has been used to profile the cellular response of macrophage-like immune cells as a result of exposure to a sub-lethal dose of particulate MoS2, as an example novel 2D material. Particles were seen to be uptaken and trafficked in sub-cellular vesicles, and this sensitive technique allows differences in the biochemical composition of the vesicles to be assessed and monitored as a function of time. Untreated macrophage-like cells contain lipidic vesicles which are found to be relatively rich in the membrane lipid sphingomyelin, key to the process of cell membrane regeneration. After exposure to MoS2, the particulate material is seen to be invaginated in similar vesicles, the most prominent of which now, however, have spectroscopic signatures which are dominated by those of phosphatidyl family lipids, consistent with the phagocytotic pathway. The lipidic content of cells is seen to increase at all time-points (4, 24 and 72 h). although vesicles composed of sphingomyelin become more prominent again following a prolonged incubation of 72 h to a sub-lethal dose of MoS2, as the immune cell has processed the particulate material and initiates recovery to a normal/untreated state. This study reveals Raman micro-spectroscopy is an effective method for monitoring cellular responses and evolution of organelle compositions in response to MoS2 exposure. The additional benefit of using this technique is that cells can be monitored as a function of time, while it can also be used for screening other micro/nano materials for toxicology and/or establishing cell responses

In-vitro Localisation and Degradation of Few-layer MoS2 Submicrometric Plates in Human Macrophage-like Cells: a Label Free Raman Micro-spectroscopic Study

Monitoring the uptake, micro-environment and fate of micro or nano scaled particulate materials in cells is of paramount importance for the emerging fields of toxicology and medicine. Such particulate materials are known to interfere with colorimetric assays and many such assays record only a single end-point. Therefore, there is a need for a label-free, cost effective technique with little or no inference from the particulate materials. Raman micro-spectroscopy was used to simultaneously interrogate the integrity of few-layer MoS2 submicrometric plates in human macrophage-like cells, in-vitro, as well as the biochemical characteristics of the local micro-environment in which they are encompassed. Firstly, the degradation profile of MoS2 plates induced by hydrogen peroxidase was established using UV-Vis absorption and Raman micro-spectroscopy. Raman micro-spectroscopic maps interrogated all aspects of the cell, including the nucleus, cytoplasm and perinuclear region, and the location/distribution of MoS2 was monitored as a function of time (4, 24 and 72 h). Whereas only pristine MoS2 was detectable after 4 and 72 periods, degradation in-vitro was confirmed following a 24 h incubation. Analysis of the MoS2 micro-environments revealed the presence of both phosphatidyl lipidic vesicles and enzymatic regions containing lysozyme, the former being most associated with the MoS2 degradation. There was an increase and saturation of cytosolic neutral lipids detected following a 24 h incubation with MoS2, which reduces following a prolonged incubation of 72 h. This study reveals that macrophage-like cells perform degradation of the material in-vitro within lipidic vesicles subsequent to phagocytosis, which manifest as an increase in the production of lipid bodies as a mechanism of defense following exposure to industrial grade MoS2

Bayesian High-Redshift Quasar Classification from Optical and Mid-IR Photometry

We identify 885,503 type 1 quasar candidates to i<22 using the combination of optical and mid-IR photometry. Optical photometry is taken from the Sloan Digital Sky Survey-III: Baryon Oscillation Spectroscopic Survey (SDSS-III/BOSS), while mid-IR photometry comes from a combination of data from the Wide-Field Infrared Survey Explorer (WISE) "ALLWISE" data release and several large-area Spitzer Space Telescope fields. Selection is based on a Bayesian kernel density algorithm with a training sample of 157,701 spectroscopically-confirmed type-1 quasars with both optical and mid-IR data. Of the quasar candidates, 733,713 lack spectroscopic confirmation (and 305,623 are objects that we have not previously classified as photometric quasar candidates). These candidates include 7874 objects targeted as high probability potential quasars with 3.5<z<5 (of which 6779 are new photometric candidates). Our algorithm is more complete to z>3.5 than the traditional mid-IR selection "wedges" and to 2.2<z<3.5 quasars than the SDSS-III/BOSS project. Number counts and luminosity function analysis suggests that the resulting catalog is relatively complete to known quasars and is identifying new high-z quasars at z>3. This catalog paves the way for luminosity-dependent clustering investigations of large numbers of faint, high-redshift quasars and for further machine learning quasar selection using Spitzer and WISE data combined with other large-area optical imaging surveys.Comment: 54 pages, 17 figures; accepted by ApJS Data for tables 1 and 2 available at http://www.physics.drexel.edu/~gtr/outgoing/optirqsos/data/master_quasar_catalogs.011414.fits.bz2 and http://www.physics.drexel.edu/~gtr/outgoing/optirqsos/data/optical_ir_quasar_candidates.052015.fits.bz