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

Essays on temporary migration

My thesis dissertation focuses on the temporariness of migration, its diverse effects as well as on migration selection. The first paper, A Dynamic Model of Return Migration analyzes the decision process underlying return migration using a dynamic model. We explain how migrants decide whether to stay or to go back to their home country together with their savings and consumption decisions. We simulate our model with return intentions and perform policy simulations. The second paper, Remittances and Temporary Migration, studies the remittance behaviour of immigrants and how it relates to temporary versus permanent migration plans. We use a unique data source that provides unusual detail on the purpose of remittances, savings, and return plans, and follows the same household over time. Our results suggest that changes in return plans lead to large changes in remittance flows. The third paper, Savings, Asset Holdings, and Temporary, analyzes how return plans affect not only remittances but also savings and the accumulation of assets. We show that immigrants with temporary return plans place a higher proportion of savings in the home country and have accumulated a higher amount and share of assets and housing value in the home country (compared to the host country). Finally, the fourth paper, Migrant Selection to the U.S.: Evidence from the Mexican Family Life Survey (MxFLS), studies the selection in terms of skills of recent migrants to the United States using the MxFLS. We highlight the important age gradient of migration, the different education attainment between age cohorts in Mexico and show the implications when analyzing migrant selection. Our claim is that in order to properly study the self-selection of migrants, it is necessary to compare migrants to non-migrants of the same age cohort

Selective epitaxial growth of graphene on SiC

We present an innovative method of selective epitaxial growth of few layers graphene (FLG) on a pre-patterned SiC substrate. The methods involves, successively, the sputtering of a thin AlN layer on top of a mono-crystalline SiC substrate and, then, patterning it with e-beam lithography (EBL) and wet etching. The sublimation of few atomic layers of Si from the SiC substrate occurs only through the selectively etched AlN layer. The presence of the Raman G-band at ~1582 cm-1 in the AlN-free areas is used to validate the concept, it gives absolute evidence of the selective FLG growth.Comment: comments: 3 pages, reference 3 replace

Invariance Violation Extends the Cosmic Ray Horizon ?

We postulate in the present paper that the energy-momentum relation is modified for very high energy particles to violate Lorentz invariance and the speed of photon is changed from the light velocity c. The violation effect is amplified, in a sensitive way to detection, through the modified kinematical constraints on the conservation of energy and momentum, in the absorption process of gamma-rays colliding against photons of longer wavelengths and converting into an electron-positron pair. For gamma-rays of energies higher than 10 TeV, the minimum energy of the soft photons for the reaction and then the absorption mean free path of gamma-rays are altered by orders of magnitude from the ones conventionally estimated. Consideration is similarly applied to high energy cosmic ray protons. The consequences may require the standard assumptions on the maximum distance that very high energy radiation can travel from to be revised.Comment: 14 pages, 1 figure, to be published in Ap J Letter

Inspecting absorption in the spectra of extra-galactic gamma-ray sources for insight into Lorentz invariance violation

We examine what the absorbed spectra of extra-galactic TeV gamma-ray sources, such as blazars, would look like in the presence of Lorentz invariance violation (LIV). Pair-production with the extra-galactic background light modifies the observed spectra of such sources, and we show that a violation of Lorentz invariance would generically have a dramatic effect on this absorption feature. Inspecting this effect, an experimental task likely practical in the near future, can provide unique insight on the possibility of LIV.Comment: Published in Phys. Rev.

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

Scanning Electron Microscopy of the Lateral Ventricle of the Pigeon Brain

Adult pigeons of both sexes were used for this study. Depending upon the distribution of various surface profiles, for example cilia, microvilli and blebs, ependymal areas with differing surface patterns were distinguished in the lateral ventricle. The topographical locations of these areas with respect to the underlying forebrain nuclei were determined in accord with the atlas of Karten and Hodos (1967). The medial surface (A) of the ventricle was much more densely ciliated than the lateral surface (B). There did not appear to be any correlation between a given surface pattern and a specific type of underlying nervous tissue. Comparison of the cell patterns seen in the pigeon brain with those seen in the analogous areas of the rat brain showed that it is not feasible to extrapolate from one zoological group to another. With the exception of the Kolmer cells populating the choroid plexus, there were remarkably few supraependymal cells in the pigeon lateral ventricle. Supraependymal nerve fibers were also extremely rare. Particular attention was given to the ependyma associated with the nucleus stria terminalis, to that of the lateral septal organ and to the choroid plexus. The possible classification of these areas into the group of the circumventricular organs is considered

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

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

Could CODA methodology be useful in control chart techniques?

On standard control charts, the hypothesis of normality is usually assumed without any additional veri cation. Nevertheless, in some cases this assumption is not accurate and might cause errors in process quality monitoring. In particular, for the control of the proportion of nonconforming units (p-chart) the normality is doubtful when p is small and consequently, lower control limit less than or equal to zero are frequent. Some authors have proposed new techniques to de ne limits in the p-chart. Others have proposed transformations to improve the detection of special causes