Is Aid for Trade Effective? A Quantile Regression Approach

This paper investigates whether Aid for Trade (AfT) improves export performance, i.e. does AfT lead to greater exports? Using panel data and panel quantile regression, our results suggest that overall AfT disbursements promote the export of goods and services mainly for the .50 and .75 quantiles. Our results also show that for some types of AfT this effect essentially vanishes at the lower tail of the conditional distribution of exports. Hence, countries that export more in volume are those benefiting most from AfT. We also investigate which types of AfT are effective. In particular, we find that aid used to build production capacity is effective. This type of aid is associated with higher exports for almost all quantiles, with the effect increasing at the upper tail of the conditional distribution. Aid used to build infrastructure is also found to affect exports at the upper tail of the distribution. In contrast, aid for trade policy and aid disbursed for general budget support (an untargeted type of aid) are not associated with greater export levels. This finding holds true irrespective of the quantile

A practical and catalyst-free trifluoroethylation reaction of amines using trifluoroacetic acid

Amines are a fundamentally important class of biologically active compounds and the ability to manipulate their physicochemical properties through the introduction of fluorine is of paramount importance in medicinal chemistry. Current synthesis methods for the construction of fluorinated amines rely on air and moisture sensitive reagents that require special handling or harsh reductants that limit functionality. Here we report practical, catalyst-free, reductive trifluoroethylation reactions of free amines exhibiting remarkable functional group tolerance. The reactions proceed in conventional glassware without rigorous exclusion of either moisture or oxygen, and use trifluoroacetic acid as a stable and inexpensive fluorine source. The new methods provide access to a wide range of medicinally-relevant functionalized tertiary beta-fluoroalkylamine cores, either through direct trifluoroethylation of secondary amines or via a three-component coupling of primary amines, aldehydes and trifluoroacetic acid. A reduction of in situ-generated silyl ester species is proposed to account for the reductive selectivity observed

Is there a common water-activity limit for the three domains of life?

Archaea and Bacteria constitute a majority of life systems on Earth but have long been considered inferior to Eukarya in terms of solute tolerance. Whereas the most halophilic prokaryotes are known for an ability to multiply at saturated NaCl (water activity (a w) 0.755) some xerophilic fungi can germinate, usually at high-sugar concentrations, at values as low as 0.650-0.605 a w. Here, we present evidence that halophilic prokayotes can grow down to water activities of <0.755 for Halanaerobium lacusrosei (0.748), Halobacterium strain 004.1 (0.728), Halobacterium sp. NRC-1 and Halococcus morrhuae (0.717), Haloquadratum walsbyi (0.709), Halococcus salifodinae (0.693), Halobacterium noricense (0.687), Natrinema pallidum (0.681) and haloarchaeal strains GN-2 and GN-5 (0.635 a w). Furthermore, extrapolation of growth curves (prone to giving conservative estimates) indicated theoretical minima down to 0.611 a w for extreme, obligately halophilic Archaea and Bacteria. These were compared with minima for the most solute-tolerant Bacteria in high-sugar (or other non-saline) media (Mycobacterium spp., Tetragenococcus halophilus, Saccharibacter floricola, Staphylococcus aureus and so on) and eukaryotic microbes in saline (Wallemia spp., Basipetospora halophila, Dunaliella spp. and so on) and high-sugar substrates (for example, Xeromyces bisporus, Zygosaccharomyces rouxii, Aspergillus and Eurotium spp.). We also manipulated the balance of chaotropic and kosmotropic stressors for the extreme, xerophilic fungi Aspergillus penicilloides and X. bisporus and, via this approach, their established water-activity limits for mycelial growth (∼0.65) were reduced to 0.640. Furthermore, extrapolations indicated theoretical limits of 0.632 and 0.636 a w for A. penicilloides and X. bisporus, respectively. Collectively, these findings suggest that there is a common water-activity limit that is determined by physicochemical constraints for the three domains of life

Evaluation of local kinetic energy dissipation rate in the impeller stream of a Rushton turbine by time-resolved PIV

International audienceThe present paper is dedicated to the direct measurement of the dissipation rate of kinetic energy, ¯ε, by means of time-resolved 2D-PIV, in the impeller region of a stirred vessel. Experimental estimation of ¯ε is carried out without simplifications, since all spatial gradients of the fluctuating velocity components are directly measured. At each point, measurements have thus been realized in three orthogonal planes. The present results have been compared with previous ones and discussed according to experimental techniques. A special attention is focused on the contribution of measurements in each plane and some newideas have been suggested for the assessment of ¯ε. In addition, in each measurement plane, the time-variation of the instantaneous fluctuating velocity gradients have been also presented, exhibiting periodicity, with large values of instantaneous dissipation rate, linked to the trailing vortex induced by the blade rotation

TITANOCENE-DICHLORIDE AS A METALORGANIC SOURCE FOR TITANIUM CARBIDE

The use of titanocene-dichloride (Cp2TiCl2) as a metalorganic precursor for TiC coating provides layers of very different quality according to its temperature of vaporization in a cold wall CVD reactor. The deposits observed by SEM and characterized by EPMA are related to the experimental procedure. The thermal behavior of the precursor investigated by thermogravimetry (TG), thermogravimetry coupled with differential thermal analysis (TG-DTA) and mass spectroscopy (MS) is used to determine the structural state of Cp2TiCl2 active from a CVD point of view

Using Classifications to Identify Pathological and Taphonomic Modifications on Ancient Bones: Do “Taphognomonic” Criteria Exist?

International audiencePathological and taphonomic agents can sometimes produce bone modifications that seem indistinguishable from one another, even to an experienced eye. The aim of this study is to propose a classification system to identify modifications observed on skeletal elements from different environmental and chronological contexts, with similar morphologies but varied aetiologies. Two types of classifications, empirical and statistical, were constructed, tested by two independent observers and compared. This classification system aims to categorise, differentiate and identify pathological and taphonomic bone modifications. In this paper, we identify several taphonomic criteria and propose a new term, “taphognomonic”, to characterise criteria that are specific to particular taphonomic agents. The two classification methods complement each other by providing precise (empirical classification) and reliable (statistical classification) diagnostic criteria. Finally, criteria are highlighted to differentiate pseudo-pathological from pathological bone modifications, the ultimate goal being to reduce the risk of misdiagnosis.Certains agents pathologiques ou taphonomiques peuvent être à l'origine de modifications osseuses tellement similaires que même un observateur aguerri ne peut les distinguer. Le but de cette étude est de proposer un outil d'identification d'un ensemble de modifications osseuses de morphologies similaires mais d'étiologies différentes, observées sur des éléments provenant d'environnements et de périodes différents. Deux systèmes de classification, empirique et statistique, ont été construits, puis testés et comparés par deux observateurs indépendants. Ces systèmes classent, différencient et identifient des modifications osseuses d'origine taphonomique ou pathologique. Cette étude a permis d'identifier plusieurs critères taphonomiques et de proposer un nouveau terme, « taphognomonique », pour caractériser des critères spécifiques à certains agents taphonomiques. Les deux types de classification sont complémentaires : ils apportent des critères diagnostiques à la fois précis (classification empirique) et fiables (classification statistique). Enfin, les critères permettant de différencier les modifications pseudopathologiques des modifications d'origine pathologique sont mis en avant, le but ultime étant de réduire le risque d'erreur diagnostique