El fin de los alimentos baratos: una mirada desde los países productores

El incremento en los precios internacionales de los alimentos está provocando tensiones económicas, sociales y políticas en diversos puntos del planeta. Este ARI comenta las múltiples causas que explican dicha subida y los desafíos que este nuevo contexto representa, focalizándose en los países productores de alimentos. La subida generalizada de las materias primas agrícolas es consecuencia de diversos factores, siendo los principales el incremento de la demanda como consecuencia del rápido crecimiento y el alza de los ingresos de países densamente poblados como China y la India (de carácter estructural), y una política de fomento a la producción de biocombustibles (en particular del obtenido a partir del maíz) que, junto al alza de los precios energéticos y el consecuente incentivo a la sustitución, generó más presión a los precios de granos y oleaginosas. Para los países pobres, importadores netos de alimentos, este nuevo escenario genera graves riesgos en materia de seguridad alimentaria. Sin embargo, y paradójicamente, también puede ocasionar importantes desafíos en aquellos países exportadores netos de alimentos por el impacto que el nuevo escenario de precios tiene sobre la pobreza y la desigualdad. Para mitigar esos efectos, resulta necesaria la implementación de programas de transferencia de ingresos y/o alimentos a los sectores más vulnerables. En un contexto financiero mundial incierto no debe soslayarse la posibilidad de utilizar otros instrumentos que, además de estimular la incorporación de valor a las materias primas exportadas por los países productores, contribuyan a contener el alza de los precios internos de los alimentos y generen recursos al Fisco

Determining 235U Enrichment Using a Dual-Energy Approach for Delayed Neutron Measurements

Bulk uranium items are often measured using active neutron interrogation systems to take advantage of the relatively high penetrability of neutrons, providing the ability to quickly and accurately measure uranium masses in large, dense configurations. Active techniques employ an external neutron source to induce fission in the uranium and subsequently measure emitted prompt fission or delayed neutrons. Unfortunately, the emitted neutrons from 235U [uranium-235] and 238U [uranium-238] are, for all practical purposes, indistinguishable; therefore, commonly used systems such as the Active Well Coincidence Counter, the 252Cf [californium-252] Shuffler, and other systems based on measurement of prompt or delayed fission neutrons require many representative calibration standards and/or well-known isotopic information to interpret the results (i.e., extract an isotopic mass from the effective fissionable mass), thus limiting these techniques for safeguards applications. The primary objective of this research was to develop and demonstrate a dual-energy neutron interrogation technique using a 252Cf Shuffler measurement chamber for determination of uranium enrichment, thus eliminating the need for a (traditionally separate) gamma isotopic measurement. This new technique exploits the change in fission rates as a function of interrogating neutron energy to independently determine the 235U and 238U content in the measurement item. Dual neutron interrogation energies were achieved by adding a deuterium- tritium (D-T) neutron generator into the measurement chamber of the Oak Ridge National Laboratory 252Cf Shuffler. Results from traditional 252Cf measurements and the new D-T measurements were then used to develop a relationship between uranium enrichment and the ratio of the two delayed neutron count rates. Parameter studies were performed to optimize the measurements for each source using a combination of modeling/simulation and experimental measurements. This dissertation presents the detailed development of this novel dual-energy neutron interrogation technique. The results are promising and with engineering refinements could be deployed for routine assay of certain types of materials

Tm3+/Ho3+ codoped tellurite fiber laser

Continuous-wave and Q-switched lasing from a Tm 3+ /Ho 3+ codoped tellurite fiber is reported. An Yb 3+ /Er 3+ -doped silica fiber laser operating at 1.6μm was used as an in-band pump source, exciting the Tm 3+ ions into the F 4 3 level. Energy is then nonradiatively transferred to the upper laser level, the I 7 5 state of Ho 3+ . The laser transition is from the I 7 5 level to the I 8 5 level, and the resulting emission is at 2.1μm . For continuous wave operation, the slope efficiency was 62% and the threshold 0.1W ; the maximum output demonstrated was 0.16W . Mechanical Q switching resulted in a pulse of 0.65μJ energy and 160ns duration at a repetition rate of 19.4kHz

Antioxidant Activity of Lutein Entrapped in Poly (DL-Lactide Co-Glycolide) Acid and PLGA/Chitosan Nanoparticles

Polymeric nanocarriers improve cellular uptake, stability, solubility, and functionality of entrapped drugs and nutraceuticals. The hypothesis of this study was that entrapping lutein, a hydrophobic antioxidant, in different polymeric nanoparticles (NPs) will improve its stability and antioxidant activity. The following objectives were proposed: 1. Synthesize and characterize polymeric nanoparticles of poly lactic co-glycolic acid (PLGA) and PLGA NPs covered with a layer of chitosan (PLGA/Chi) from a physicochemical perspective, and 2. Assess functionality of the entrapped lutein as a function of type of polymer in which entrapped. Nanoparticles were synthesized by emulsion evaporation method. Characterization included size, zeta potential, and morphology measurement, followed by testing the physical and chemical stability, and antioxidant activity of entrapped lutein. PLGA NPs loaded with lutein were in the size range of 119.2 nm ± 0.98 nm with a PDI of 0.17± 0.02 and a zeta potential of – 29 mV ± 1.1 mV in nanopure water with 0.05 mg PVA/ mg PLGA ± 0.002 mg PVA/ mg PLGA remaining on the surface of the nanoparticles. PLGA/Chi NPs loaded with lutein were in the size range of 145.9 ± 0.3 nm with a PDI of 0.25 ± 00.01 and a zeta potential of 21.2 mV ± 2.3 mV with 0.06 mg ± 0.002 mg PVA/ mg PLGA/Chi remaining in nanopure water. PLGA NPs and PLGA/Chitosan NPs loaded with lutein were stable in emulsions made with Tween 20 for 72 hours at 37 °C as indicated by a constant size over time. PLGA and PLGA/Chi NPs protected the chemical stability of lutein in Tween 20 emulsions for 24 hours at 37 °C. PLGA and PLGA/Chitosan NPs showed significant reductions in the oxidation of cholesterol by 45 ± 1% and 60 ± 1 % at 48 hours, and 36 ± 1 % and 42 ± 3 % at 72 hours when compared to the free lutein. The addition of chitosan to the PLGA NPs further enhanced the efficacy of lutein as an antioxidant when compared to PLGA NPs. These results support the hypothesis that polymeric NPs are enhancing stability and antioxidant activity of entrapped lutein and hence may find beneficial applications in the biomedical and food science fields for delivery of lutein

L'Observatoire juridique transfrontalier Iuris Muga

1990, iniciativas diversas para acercar a los juristas de ambos lados. 1994, Convención de los dos Colegios de Abogados. 1997, señales de agotamiento del proyecto. 1998, interés Facultades Derecho de Bayona y San Sebastián en proyectos jurídicos transfronterizos. 1998 a 2000, trabajos preparatorios del Observatorio. 1999, subvención al proyecto por Euskadi-Aquitania. Octubre del 2000, constitución de AEIE. Objetivos: conocimiento y compilación pequeña Jurisprudencia Tribunales de ambos lados, análisis y difusión de datos y formación en Derecho transfronterizo..1990, hainbat ekimen alde bietako juristak elkarrengana hurbiltzeko. 1994, Abokatuen Elkargo bietako Hitzarmena. 1997, proiektua agortzen ari zeneko seinaleak. 1998, Baiona eta Donostiako Zuzenbide Fakultateak mugaz gaindiko proiektu juridikoetan interesaturik. 1998tik 2000ra, Behakundearen prestalanak. 1999, Euskadi-Akitaniaren dirulaguntza proiektuarentzat. 2000ko urria, AEIE delakoa eraturik. Helburuak: alde bietako Auzitegietako Jurisprudentzia txikia ezagutzea eta biltzea, datuen azterketa eta zabalkundea eta Mugaz gaindiko Zuzenbidean prestakuntza ematea.1990, diverses initiatives pour rapprocher les juristes des deux côtés. 1994, Convention des deux Barreaux. 1997, signes d'épuisement du projet. 1998, intérêt des Facultés de Droit de Bayonne et Saint-Sébastien pour des projets juridiques transfrontaliers. 1998 à 2000, travaux préparatoires de l'Observatoire. 1999, subvention au projet pour Euskadi-Aquitaine. Octobre 2000, constitution de AEIE. Objectifs: connaissance et petite compilation Jurisprudence Tribunaux des deux côtés, analyse et diffusion de données et formation en Droit transfrontalier..In 1990, there were various initiatives to bring together the jurists of both sides. In 1994, a Convention of the two Bar Associations was held. In 1997, there were signs that the project had exhausted its possibilities. In 1998, there was some interest in the Law Faculties of Bayonne and San Sebastian on transborder legal projects. From 1998 to 2000, the observatory preparatory projects were carried out. In 1999, the project was subsidised by Euskadi-Aquitaine. In October 2000, the AEIE was constituted. Its objective is the knowledge and compilation of jurisprudence from the Courts of both sides, its analysis and transborder law data and training dissemination

Energy level decay processes in Ho3+-doped tellurite glass relevant to the 3-µm transition

The primary excited state decay processes relating to the 5I6 --> 5I7 at 2.9 um laser transition in singly Ho3+-doped tellurite (TZBG) glass have been investigated in detail using time-resolved fluorescence spectroscopy. Selective laser excitation of the 5I6 energy level at 1151 nm and 5I7 energy level at 1958 nm has established that the rate of energy transfer up-conversion between holmium ions excited to the 5I7 level is negligible for Ho3+ concentrations up to 4 mol. %. Excited state absorption was not observed from either the 5I7 or 5I6 levels and the luminescence from the 5I7 and 5I6 energy levels was measured to peak at 2050 nm and 2930 nm, respectively. The 5I6 level has a low luminescence efficiency of 8.9% due to strong nonradiative multiphonon relaxation. In contrast, decay from the 5I7 level is essentially fully radiative. A linear decrease in the decay time of the 5I6 level with Ho3+ concentration augmentation results from energy transfer to OH ions in the glass (with NOH=8.2x10^17 ions cm^-3) and reduces the luminescence efficiency of the 5I6 level to 8% for [Ho3+]=4 mol. %. Numerical simulation of a fiber laser incorporating 4 mol. % Ho3þ showed that a population inversion of 7.8% is reached for square pulses of 100 us duration and a repetition frequency of 20 Hz at a moderate pump intensity of 418 kW cm^-2 if energy transfer to OH- radicals is neglected

TeO2-ZnO-La2O3 glass composition for mid infrared wavelengths generation and transmission in optical fibers

Numerous applications in the Mid InfraRed (Mid IR) wavelength region still require basic optical components such as sources and optical fibers as transmission medium. Thanks to its mid IR transparency and nonlinearity, tellurite glass allows for developing both these types of components. However, practical applications require materials able to handle high optical intensity through enhanced material damage threshold. We report on the synthesis of a tellurite glass in the TeO2-ZnO-La2O3 (TZL) system which presents enhanced thermo mechanical properties with respect to typical tellurite glass compositions. We measured for the TZL composition a glass transition of 626 K, hence 70 K higher than the glass transition temperature of “standard” TZN compositions. The coefficient of thermal expansion was measured to be 138.10-6/K as compared to typical value of 180.10-6/K for TZN glass. We manufactured two types of fibers to assess the prospect for achieving high average power SC sources and Mid IR transmission in TZL glass fibers. First, a high Numerical Aperture (NA) aperture fiber was developed through standard rod in tube technique, where the cladding glass tube was manufactured by extrusion. The 50 μm core fiber presents an optical attenuation value of 0.26 dB/m at 1.55 μm. As an intermediate step towards the fabrication of an antiresonant hollow core fiber for high power transmission, we manufactured a preform and drew it into a cane. A TZL glass tube, 120 mm long and 9 mm/12 mm of inner/outer diameters (ID/OD) was manufactured via rotational casting technique. This latter tube was drawn into a tube of 2 mm in diameter which was cut into sections 130 mm long. Seven of those were stacked in another tellurite glass tube 6.5 mm/12 mm of ID/OD diameters, respectively. This preform was then drawn into a microstructured cane 1.6 mm in diameter which features tubular structures periodically arranged and of uniform thickness

Desktop Analysis Reporting Tool (DART) User's Guide

The Desktop Analysis Reporting Tool (DART) is a software package that allows a user to easily view and analyze radiation portal monitor (RPM) daily files that span long periods. DART gives users the capability to determine the state of health of a monitor, troubleshoot and diagnose problems, and view data in various time frames to perform trend analysis. In short, it converts the data strings written in the daily files into meaningful tables and plots. DART is an application-based program that was designed to maximize the benefit of a centralized data repository while distributing the workload to individual desktop machines. This networked approach requires a more complex database manager (SQL Server); however, SQL Server is not currently provided with the DART Installation Disk. SQL Express is sufficient for local data analysis and requires the installation of SQL Express and DART on each machine intended for analysis

Yb-doped phosphate double-cladding optical fiber laser for high-power applications

A Yb-doped phosphate glass double cladding optical fiber was prepared using a custom designed glass composition (P2O5 - Al2O3 - Li2O - B2O3 - BaO - PbO - La2O3) for high-power amplifier and laser applications. The preform drawing method was followed, with the preform being fabricated using the rotational casting technique. This technique, previously developed for tellurite, fluoride or chalcogenide glass preforms is reported for the first time using rare earth doped phosphate glasses. The main challenge was to design an adequate numerical aperture between first and second cladding while maintaining similar thermo-mechanical properties in view of the fiber drawing process. The preform used for the fiber drawing was produced by rod-in-tube technique at a rotation speed of 3000 rpm. The rotational casting technique allowed the manufacturing of an optical fiber featuring high quality interfaces between core and internal cladding and between the internal and external cladding, respectively. Loss attenuation was measured using the cut-back method and lasing was demonstrated at 1022 nm by core pumping with a fiber pigtailed laser diode at the wavelength of 976 n

Highly Doped Phosphate Glass Fibers for Compact Lasers and Amplifiers: A Review

In recent years, the exploitation of compact laser sources and amplifiers in fiber form has found extensive applications in industrial and scientific fields. The fiber format offers compactness, high beam quality through single-mode regime and excellent heat dissipation, thus leading to high laser reliability and long-term stability. The realization of devices based on this technology requires an active medium with high optical gain over a short length to increase efficiency while mitigating nonlinear optical effects. Multicomponent phosphate glasses meet these requirements thanks to the high solubility of rare-earth ions in their glass matrix, alongside with high emission cross-sections, chemical stability and high optical damage threshold. In this paper, we review recent advances in the field thanks to the combination of highly-doped phosphate glasses and innovative fiber drawing techniques. We also present the main performance achievements and outlook both in continuous wave (CW) and pulsed mode regimes