Resumen El objetivo de la presente revisión científica fue sistematizar información bibliográfica actualizada, concerniente a los aspectos genéticos, morfológicos, zootécnicos y potencial carnicero de los cerdos criollos de Latinoamérica encontró una población de 73 millones de cerdos criollos en Latinoamérica, la mayoría de ellos criados bajo sistemas de producción extensivos, semiextensivos y agro pastoriles. Dado su origen europeo, la adaptación a los diferentes ecosistemas del continente y la introducción de razas ha devenido en una gran diversidad de cerdos criollos, lo que ha dado origen al aumento de variabilidad genética de los cerdos criollos latinos beneficiando su rusticidad, que involucra una mayor eficiencia del sistema inmunológico. De la misma manera, su calidad de omnívoro le permitió una buena adaptación a regímenes alimentarios variados. Los cerdos criollos manifiestan un comportamiento reproductivo aceptable, tomando como referencia los indicadores de producción intensiva, precocidad sexual y alta viabilidad de los lechones al destete; sin embargo, su crecimiento es lento y su periodo de lactancia es largo. Con respecto a la calidad de sus cortes cárnicos, tomando en cuenta criterios subjetivos como la terneza y el valor nutricional, el cerdo criollo tiene mayor valor económico aventajando a los cerdos hipermagros.

We have grown epitaxial thin films of multiferroic BiMnO 3 using pulsed laser deposition. The films were grown on SrTiO 3 (001) substrates by ablating a Bi-rich target. Using x-ray diffraction we confirmed that the films were epitaxial and the stoichiometry of the films was confirmed using Auger electron spectroscopy. The films have a ferromagnetic Curie temperature (T C) of 85±5 K and a saturation magnetization of 1 µ B /Mn. The electric polarization as a function of electric field (P − E) was measured using an interdigital capacitance geometry. The P − E plot shows a clear hysteresis that confirms the multiferroic nature of the thin films. PACS numbers: Valid pacs appear here Multiferroic materials are unique in that they exhibit both ferromagnetism and ferroelectricity simultaneously. 1 Such materials may be used to fabricate devices such as magnetic tunnel junctions with electrically tunable tunneling magnetoresistance and multiple state memory elements. 2 The recent interest in multiferroics is fueled both by the potential device applications and questions about the underlying physical principles leading to multiferroism. 3-7 Bulk multiferroic materials are rare, possibly due to conflicting requirements for ferromagnetism (FM) and ferroelectricity (FE). BiMnO 3 is perhaps the most fundamental multi-ferroic and has been referred to as the "hydrogen atom" of multiferroics. 8 In BiMnO 3 (BMO), as in BiFeO 3 , the 6s 2 lone pair on the Bi-ion leads to the displacement of that ion from the centrosymmetric position at the A-site of a perovskite unit cell. The resultant distortion leads to an FM interaction between the Mn-ions at the B-site in BMO. 9,10 In bulk form BMO has been observed to be both FM and FE. 11 Polycrystalline BMO can be grown under high pressure and within a very narrow range of growth conditions. While thin films of BMO have been grown by various groups, few such films have shown magnetic properties similar to bulk BMO and high enough resistivities i.e. low leakage currents to allow clear measurement of FE properties. 12-14 A possible reason for the low resistivities of BMO thin films is the substrate induced strain which exacerbates the growth of a highly distorted perovskite structure. Additionally, recent electron and neutron diffraction data have cast doubt over the purported non-centrosymmetry of the BMO crystal structure 15 and centrosymmetric structures have also been predicted using density functional theory calculations 16. Since a non-centrosymmetric crystal structure is essential for ferroelectricity, the observed ferroelectric behavior of BMO may be due to strain and/or ordered oxygen vacancies. 17,18 BMO has a distorted perovskite-type structure with a = c = 3.935Å935Å (α = γ = 91.4 •) and b = 3.989Å 989Å (β = 91 •). 20 Fig. 1 shows the larger monoclinic unit cell of BMO 9 ; we have used the monoclinic notation to index the x-ray diffraction data of our thin films. Since cubic SrTiO 3 (STO) has a lattice parameter of 3.905Å905Å, BMO grows with an (111) orientation on STO (001) sub-...

Caracterización de cepas nativas deResumen La presente investigación se realizó para caracterizar y determinar el efecto de cepas nativas de Azospirillum spp. en el desarrollo de Oryza sativa L "arroz", como una alternativa para la disminución de fertilizantes químicos. Las bacterias se aislaron de raíces de arroz en Lambayeque. Fragmentos de raíces previamente desinfectadas se sembraron en medio Nfb semisólido, donde las bacterias fijadoras de nitrógeno se reconocieron por una película blanquecina bajo la superficie y el viraje del verde al azul. El género Azospirillum se identificó en medio agar rojo de Congo, obteniéndose 96 cepas con una producción de 2.69 a 38.02 ppm de ácido indolacético y 7.95 a 29.09 ppm de nitrógeno fijado. Las cuatro cepas con los mayores valores se inocularon independientemente así como en combinación con 50 y 100 % de úrea, en arroz INIA508-Tinajones. Se utilizó un diseño experimental completamente aleatorio, incluyendo testigos 50 y 100 % de úrea y testigo absoluto, Todas las cepas nativas incrementaron la altura y materia seca de la parte aérea y raíces, con índices de efectividad de hasta 21.77, 102.06 y 126.11% en relación al testigo absoluto. Azospirillum sp. GM-86 seleccionado por el mayor valor de ácido indolacético, alcanzó el mayor índice de efectividad en altura y biomasa seca de raíz. La aplicación de 50 % de úrea con Azospirillum spp. incrementó los índices de efectividad. Se demostró el potencial de cepas nativas de Azospirillum spp. para incrementar el desarrollo de arroz, así como la posibilidad de utilizarlas asociadas con dosis mínimas de úrea.Palabras clave: Azospirillum, PGPR , Oryza sativa L., indolacético, nitrógeno. AbstractThis research was conducted to characterize and determine the effect of native strains of Azospirillum spp. on growth of Oryza sativa L. "rice" as an alternative for the reduction of chemical fertilizers. The bacteria were isolated from roots of rice in Lambayeque. Fragments of previously disinfected roots were planted in Nfb semisolid medium, were nitrogen-fixing bacteria were recognized by a whitish film on the surface and turn from green to blue. The genus Azospirillum was identified in Congo red agar medium, obtained 96 isolates with production of 2.69 to 38.02 ppm indoleacetic acid and 7.95 to 29.09 ppm of fixed nitrogen. The four strains with the highest values were inoculated independently and in combination with 50 and 100 % urea in Tinajones INIA508 rice. It used a completely randomized design and including witnesses' 50 and 100 % urea and absolute control. All native strains increased height and dry matter of shoot and roots, with effectiveness index of up to 21.77, 102.06 and 126.11 % compared to untreated control. Azospirillum sp. GM-86 selected by the highest value of indoleacetic acid, reached the highest level of effectiveness in height and root dry biomass. The application of 50 % úrea with Azospirillum spp. increased rates of effectiveness. It demonstrated the potential of native strains of Azospirillum spp. to increase the g...

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