Forecasting Agricultural Commodity Prices with Asymmetric-Error GARCH Models

The performance of a proposed asymmetric-error GARCH model is evaluated in comparison to the normal-error- and Student-t-GARCH models through three applications involving forecasts of U.S. soybean, sorghum, and wheat prices. The applications illustrate the relative advantages of the proposed model specification when the error term is asymmetrically distributed, and provide improved probabilistic forecasts for the prices of these commodities.GARCH, nonnormality, skewness, time-series forecasting, U.S. commodity prices, Demand and Price Analysis,

COLLECTIVE ACTION AND INFORMAL FINANCIAL INSTITUTIONS: AN EMPIRICAL ANALYSIS OF ROTATING AND SAVINGS CREDIT ASSOCIATIONS (ROSCAS) IN SENEGAL

This study analyzes how rotating savings and credit associations (ROSCAs) in Senegal were able to overcome the collective action dilemma, maintain institutional performance, and remain sustainable over time. This study models cooperation among members as well as the performance and sustainability of associations using data collected from field research conducted in Dakar, Senegal in 2001. The results show that factors such as homogeneity of individuals within an association, how long the association has existed, how defaults are covered, and rules such residency requirements, individual contributions, and rotation order are to various degree critical to the performance and sustainability of ROSCAs and to the fostering of cooperation among members of these associations.Financial Economics,

The Political and Economic Determinants of Trade Disputes under the WTO

Replaced with revised version of paper 02/25/08.democratization, system of government, trade disputes, World Trade Organization (WTO), economic strata, International Relations/Trade, P16, F13,

Synthesis, characterisation and antimicrobial activities of cobalt(II), copper(II) and zinc(II) mixed-ligand complexes containing 1,10-phenanthroline and 2,2’-bipyridine

Three new 1,10-phenanthroline and 2,2’-bipyridine mixed-ligand complexes of [Co(bpy)(phen)2](NO3)2.2H2O, [Cu(bpy)(phen) H2O)2]Cl2.2H2O, and [Zn(bpy)2(phen)]Cl2.6H2O were synthesized. The complexes were characterized by elemental, IR and visible spectroscopic analyses and the results indicate that both ligands are coordinated to the respective metal ions giving octahedral complexes. Antimicrobial studies showed that there is increased antimicrobial activity of the metal ions on coordination to the ligands. The water soluble complexes showed antimicrobial activities that are higher than those of the metal salts and 2,2’-bipyridine but lower than those of 1,10-phenanthroline. The copper complex [Cu(bpy)(phen)(H2O)2]Cl2.2H2O shows the highest activity. KEY WORDS: 1,10-Phenanthroline, 2,2’-Bipyridine, Mixed-ligand complexes, Antimicrobial activities, Cobalt(II), Copper(II), Zinc(II)Bull. Chem. Soc. Ethiop. 2010, 24(3), 383-389

Physicochemical typology of water of a middle atlas river (Morocco) where the common trout (Salmo trutta macrstigma, Duméril, 1858) live: Oued Sidi Rachid

For every live being, ecological conditions greatly influence biology. In the case of a fish, these conditions may be responsible for its presence or absence in the medium, its development and its population size. This work studies the characteristics and physicochemical typology of Sidi Rachid River, known by its wealth of the Salmonidae fish: Salmo trutta macrostigma (Duméril, 1858). The results show that apart from the appearance of nitrates, whose high levels indicate an organic pollution, during some times of the year, coming seemingly from the Ras Elma fish farm waste water, the water quality is good. The results also show that the physico-chemical typology of the watercourse is mainly influenced by the "season" factor and that among the studied variables, only the pH does not influence the spatial and temporal variation of the medium studied characteristics.Key words: Sidi Rachid River, physicochemical typology, Salmo fario, Morocco

The quasi-biennial oscillation (QBO) and global-scale tropical waves in Aeolus wind observations, radiosonde data, and reanalyses

The quasi-biennial oscillation (QBO) of the stratospheric tropical winds influences the global circulation over a wide range of latitudes and altitudes. Although it has strong effects on surface weather and climate, climate models have great difficulties in simulating a realistic QBO, especially in the lower stratosphere. Therefore, global wind observations in the tropical upper troposphere and lower stratosphere (UTLS) are of particular interest for investigating the QBO and the tropical waves that contribute significantly to its driving. In our work, we focus on the years 2018–2022 and investigate the QBO and different tropical wave modes in the UTLS region using global wind observations made by the Aeolus satellite instrument and three meteorological reanalyses: the fifth generation European Centre for Medium-Range Weather Forecasts (ECMWF) reanalysis (ERA-5), the Japanese 55-year Reanalysis (JRA-55) of the Japan Meteorological Agency (JMA), and the Modern-Era Retrospective Analysis for Research and Applications, version 2 (MERRA-2). Further, we compare these data with observations of selected radiosonde stations. By comparison with Aeolus observations, we find that, on zonal average, the QBO in the lower stratosphere is well represented in all three reanalyses, with ERA-5 performing best. Averaged over the years 2018–2022, agreement between Aeolus and the reanalyses is better than 1 to 2 m s−1, with somewhat larger differences during some periods. Differently from zonal averages, radiosonde stations provide only local observations and are therefore biased by global-scale tropical waves, which limits their use as a QBO standard. While reanalyses perform well on zonal average, there can be considerable local biases between reanalyses and radiosondes. We also find that, in the tropical UTLS, zonal wind variances of stationary waves and the most prominent global-scale traveling equatorial wave modes, such as Kelvin waves, Rossby-gravity waves, and equatorial Rossby waves, are in good agreement between Aeolus and all three reanalyses (in most cases better than 20 % of the peak values in the UTLS). On zonal average, this supports the use of reanalyses as a reference for comparison with free-running climate models, while locally, certain biases exist, particularly in the QBO wind shear zones and around the 2019–2020 QBO disruption.</p

1,1-Diethyl-3-(4-meth­oxy­benzo­yl)thio­urea

In the title compound, C13H18N2O2S, the 4-meth­oxy­benzoyl fragment is approximately planar [maximum deviation = 0.057 (2) Å] and twisted relative to the thio­amide fragment, forming a dihedral angle of 86.62 (6)°. The two Csp 2—Nsp 2 bonds in the thio­urea unit differ significantly in length [1.327 (2) and 1.431 (2) Å]. In the crystal, N—H⋯O hydrogen bonds link the mol­ecules into chains parallel to [010]

Research Brief: Value chain and market potential of Bambara groundnut to strengthen climate resilience, food security and women’s income in Mali

This value chain analysis was carried out by Charlie Mbosso in collaboration with Aminata Berthe Niang, Youssoufa Mohamadou, Stefano Padulosi, Amadou Sidibe, and Gennifer Meldrum as part of the project "Linking Value Chains of Agricultural Biodiversity to Adaptation to Climate Change and Nutrition: Empowering the Poor for Risk Management "funded by the International Fund for Agricultural Development (IFAD), the European Union (EU) and the Research Programs of CGIAR Centers on Climate Change, Agriculture and Security (CCAFS) and Agriculture for Nutrition and Health (A4NH

Synthesis and characterization of analogues of glycine-betaine ionic liquids and their use in the formation of aqueous biphasic systems

A series of novel analogues of glycine-betaine ionic liquids (AGB-ILs), viz. 1-(4-ethoxy-4-oxobutyl)-1-methylpyrrolidin-1-ium, N,N,N-tri(n-butyl)(4-ethoxy-4-oxobutyl)-1-phosphonium and N,N,N-trialkyl(4-ethoxy-4-oxobutyl)-1-aminium cations with ethyl, n-propyl and n-butyl alkyl chains, combined with the bromide anion, have been synthesized and characterized. Their synthesis and characterization by spectroscopic methods and elemental analysis is here reported. These ILs were further characterized in what concerns their thermal properties and ecotoxicity against Allvibrio fischeri, and compared with the commercial tetra(n-butyl)ammonium and tetra(n-butyl)phosphonium bromide. The novel AGB-ILs described in this work have low melting points, below 100 °C, display high degradation temperatures (180–310 °C), and low toxicity as shown by being harmless or practically harmless towards the marine bacteria Allvibrio fischeri. Finally, the ability of the synthesized AGB-ILs to form aqueous biphasic systems with potassium citrate/citric acid (at pH 7) was evaluated, and the respective ternary phase diagrams were determined. It is shown that the increase of the cation alkyl chain length facilitates the creation of ABS, and that phosphonium-based ILs present a slightly better separation performance in presence of aqueous solutions of the citrate-based salt.publishe