Remittances and temporary migration

In this paper we study the remittance behavior of immigrants and how it relates to temporary versus permanent migration plans. We use a unique data source that provides unusual detail on remittances and return plans, and follows the same household over time. Our data allows us also to distinguish between different purposes of remittances. We analyze the association between individual and household characteristics and the geographic location of the family as well as return plans, and remittances. The panel nature of our data allows us to condition on household fixed effects. To address measurement error and reverse causality, we use an instrumental variable estimator. Our results show that changes in return plans are related to large changes in remittance flows

Small scale production and storage quality of drymilled degermed maize products for tropical countries

The present study aims to propose a comprehensive appropriate technological package for small-scale processing of maize flour, which meets consumer demand for quality and achieves extended shelf life.One traditional soft cultivar was processed by the conventional method (direct grinding with disc mill) and was compared with flours obtained under various degerming and grinding intensities; two types of grinder (disc mill and hammer mill, already present on the market) were tested in parallel. Consumer satisfaction scores were registered for the different products after increasing storage duration (0 to 6 months). It was shown that combining degerming and hammer milling produce high quality flour from hard grains, which can be stored up to 6 months without significant deterioration. In parallel, physicochemical and rheological  haracterizations showed that the main reaction occurring during storage is lipid degradation, which slightly increased fat acidity, hence decreasing taste and elasticity acceptability of the paste

Growth of monolayer graphene on 8deg off-axis 4H-SiC (000-1) substrates with application to quantum transport devices

Using high temperature annealing conditions with a graphite cap covering the C-face of an 8deg off-axis 4H-SiC sample, large and homogeneous single epitaxial graphene layers have been grown. Raman spectroscopy shows evidence of the almost free-standing character of these monolayer graphene sheets, which was confirmed by magneto-transport measurements. We find a moderate p-type doping, high carrier mobility and half integer Quantum Hall effect typical of high quality graphene samples. This opens the way to a fully compatible integration of graphene with SiC devices on the wafers that constitute the standard in today's SiC industry.Comment: 11 pages, 4 figures , Submitted in AP

Optimisation de la fermentation en milieu semi-solide pour la production d’ablo, pain cuit a la vapeur d’Afrique de l’ouest

Objectif : Evaluer trois équipements pour la fermentation de la pâte destinée à préparer l’ablo (pâte cuite à la vapeur) puis, l’influence de la température, de la durée de fermentation et du taux de levure ajoutée à la pâte.Méthodologie et résultats : La pâte semi-solide a été fermentée durant quatre heures à température ambiante (26-27 °C) dans du bac en verre, glacière et bassine en aluminium (Témoin). En outre, l’effet de la température, de la durée de fermentation et du taux de levure a été évalué à travers un dispositif factoriel complet dont les niveaux bas et hauts des facteurs rangeaient entre 2 et 6 heures, 22 et 30 °C et 1 et 3 g/Kg de farine. La pousse, le pH, l’acidité titrable et la charge en levures/moisissures ont été déterminés. A l’exception de la quantité de mousse produite et de la matière sèche, aucun effet significatif (P>0,05) du matériel de fermentation n’a été mis en évidence sur les paramètres mesurés. Le taux de levure, la température et la durée de fermentation avaient une influence positive significative (P<0,05) sur la quantité de mousse produite.Conclusion et application : Le dispositif en verre, suivi de la glacière, avaient généré la plus grande quantité de mousse, probablement à cause d’une relative herméticité ou de la forme géométrique régulière des deux dispositifs. Au rendement en pâte voisin de 180, la fermentation dans les conditions optimales validées exigeait 30 °C, 3 g de levure par Kg de farine de riz et 4 h de conditionnement ; ce qui donne une pâte fermentée possédant un pH compris entre 4,42 et 4,64, une teneur de matière sèche variant entre 29,99 et 38,79% et la variation de hauteur de la mousse comprise entre 4,85 et 5,62 cm. Il serait intéressant de tester ces conditions optima de fermentation sur autres matières premières (maïs, mélange riz-maïs) intervenant dans la production d’ablo.Mots clés : Ablo, levures, optimisation, fermentation, rizOptimization of semi-solid state fermentation for processing ablo, a wet steamed bread from West AfricaObjective: To test three equipments for the fermentation of rice semi-solid dough to produce ablo (a steamy and foamy bread) and then, to investigate the effect of fermentation temperature and duration and the rate of yeast on some critical parametersMethodology and results: The semi-solid dough was fermented for four hours in glass box, icebox and aluminum bowls (Control) at ambient temperature (26-27 °C). In addition, the effect of fermentation temperature and duration and the rate of yeast were investigated using full factorial design, with values ranging between 2 and 6 hours, 22 and 30 °C and 1 and 3 g/Kg flour. The pH, titrable acidity, the dry matter content and the quantity of moss/foam were determined as well as the yeast and fungi counts. Except for the moss produced and the dry matter content, no significant effect was evidenced on all other parameters measured as far as the equipment is considered. Significant and positive effects of temperature, duration and the rate of yeast (P<0.05) were observed on the quantity of moss producedConclusion and application: The glass box, followed by icebox were the best fermenting equipments of the dough, giving great amount of moss produced, probably due the airtight or the regular form of both equipments. At the dough yield of 180, the optimal values of these factors for upgrading fermentation of the rice dough included 30 °C, 3 g of yeast per Kg of flour and 4 hours of resting. These conditions was validated and lead to the fermented dough with pH ranging between 4.42 and 4.64, dry matter between 29.99 et 38.79% and moss height varying from 4.85 to 5.62 cm. In further work, it will be appreciated to test these optima conditions on maize or the mix rice-maize flour since they are raw materials for ablo productionKeywords: Yeast, optimization, fermentation, Abl

Modeling lactic fermentation of gowé using Lactobacillus starter culture

A global model of the lactic fermentation step of gowé was developed by assembling blocks hosting models for bacterial growth, lactic acid production, and the drop of pH during fermentation. Commercial strains of Lactobacillus brevis and of Lactobacillus plantarum were used; their growth was modeled using Rosso's primary model and the gamma concept as a secondary model. The optimum values of pH and temperature were 8.3 ± 0.3, 44.6 ± 1.2 °C and 8.3 ± 0.3, 3.2 ± 37.1 °C with μmax values of 1.8 ± 0.2 and 1.4 ± 0.1 for L. brevis and L. plantarum respectively. The minimum inhibitory concentration of undissociated lactic acid was 23.7 mM and 35.6 mM for L. brevis and L. plantarum, respectively. The yield of lactic acid was five times higher for L. plantarum than for L. brevis, with a yield of glucose conversion to lactic acid close to 2.0 for the former and 0.8 for the latter. A model was developed to predict the pH drop during gowé fermentation. The global model was partially validated during manufacturing of gowé. The global model could be a tool to aid in the choice of suitable starters and to determine the conditions for the use of the starter. (Résumé d'auteur

Self-consistency in Theories with a Minimal Length

The aim of this paper is to clarify the relation between three different approaches of theories with a minimal length scale: A modification of the Lorentz-group in the 'Deformed Special Relativity', theories with a 'Generalized Uncertainty Principle' and those with 'Modified Dispersion Relations'. It is shown that the first two are equivalent, how they can be translated into each other, and how the third can be obtained from them. An adequate theory with a minimal length scale requires all three features to be present.Comment: typos corrected, published with new title following referee's advic

Synthesis, thermogravimetric and high temperature X-ray diffraction analyses of zinc-substituted nickel manganites

Stoichiometric spinel phases Mn2.352xNi0.65ZnxO4 were prepared by thermal decomposition of mixed oxalate precursor powders Mn0.782aNi0.22ZnaC2O4znH2O (with 0 # a # 0.53) at 900°C. Cation-deficient phases Mn2.352xNi0.65Znxh3d/4O41d were identified in the temperature range 350–500°C. The nonstoichiometric coefficient d was found to strongly depend on the zinc content and the decomposition temperature. We showed that the introduction of zinc into the spinel phase enlarges the stability domain of the structure and inhibits oxidation at least up to 900°C. A cubic single-phase was observed for x # 1.00. The lattice parameter variation of the oxides in the composition range 0 # x # 0.60 can be explained using Poix’s method, in terms of the distribution of Zn21 cations on the tetrahedral sites. However, for higher zinc content (x . 0.6) a detailed analysis of data showed that a small fraction of Zn21 is located on octahedral sites

Nuclear recoil measurements in Superheated Superconducting Granule detectors

The response of Superheated Superconducting Granule (SSG) devices to nuclear recoils has been explored by irradiating SSG detectors with a 70Me$\!$V neutron beam. In the past we have tested Al SSG and more recently, measurements have been performed with Sn and Zn detectors. The aim of the experiments was to test the sensitivity of SSG detectors to recoil energies down to a few ke$\!$V. In this paper, the preliminary results of the neutron irradiation of a SSG detector made of Sn granules 15-20$\mu$m in diameter will be discussed. For the first time, recoil energy thresholds of $\sim$1ke$\!$V have been measured.Comment: 7pages in Latex format, Preprint Bu-He 93/6 (University of Berne, Switzerland), four figures available upon request via [email protected] or [email protected]

X-ray diffraction, thermal analysis, and Raman scattering study of K2BeF4 and comparation to other member of the (beta)-K2SO4 family with ferroelectric -paraelectric transition

Thermal analysis, powder diffraction, and Raman scattering as a function of the temperature were carried out on K2BeF4. Moreover, the crystal structure was determined at 293 K from powder diffraction. The compound shows a transition from Pna21 to Pnam space group at 921 K with a transition enthalpy of 5 kJ/mol. The transition is assumed to be first order because the compound shows metastability. Structurally and spectroscopically the transition is similar to those observed in (NH4)2SO4, which suggests that the low-temperature phase is ferroelectric. In order to confirm it, the spontaneous polarization has been computed using an ionic model