Sputniks cubanos. De cómo la URSS ocupó la imaginación de una generación

Resumen: A pesar de la cierta marginalidad de la ciencia ficción en Cuba, ésta no estuvo exenta de la influencia cultural que sufrió la isla al sovietizarse. De la URSS y el entorno comunista llegaron cientos de obras del género, al mismo tiempo que la producción local se reducía a cero en los años setenta. Los autores cubanos tomaron partido, unos defendieron los nuevos estilos e ideas venidos del Este; otros decidieron seguir su camino, algunas veces, a contracorriente.  Despite the somewhat marginalization of science fiction in Cuba, the genre could not avoid the cultural influence that the island experienced when it adopted Soviet cannons. From the USSR and the Communist allies came hundreds of genre publications in the seventies, while local production was reduced to zero. Most Cuban writers took sides, some defended the new styles and ideas that came from the East; others decided not to, and even created sometimes a counter discourse

Diversity of N2-fixing cyanobacteria from Andalusian paddy fields and analysis of their potential as bioinoculants

The marshes of the Guadalquivir River contain the largest area of rice cultivation in Spain, where more than 40,000 ha are used every year for rice production. These wetland areas provide a perfect place for rice cultivation, and represent a unique aquaticterrestrial habitat that hold more wintering waterfowl than any other European wetland. Paddies require large amounts nitrogen and phosphorus for their growth, development and production. Though, flooded conditions used for rice cultivation drastically diminish efficiency inorganic nitrogen fertilizers, being only 30–40% used by the plant, and in some cases even less. Large amounts of nitrogen fertilizers are dissolved in the surface water and lost, causing environmental pollution and health problems due to losses through N2O and NO volatilization, denitrification, and leaching (Ishii et al., 2011)

Monitoring of evoked potentials during spinal cord ischaemia: Experimental evaluation in a rabbit model

Objectives:somatosensory evoked potentials (SEPs), spinal evoked potentials (Spinal-EPs), and motor-evoked potentials (MEPs) were monitored in a rabbit model of spinal cord ischaemia to evaluate their accuracy and relationship to clinical status.Methods:a modified rabbit spinal cord ischaemia model of infrarenal aortic occlusion for 21 min was employed (30 rabbits). After baseline SEPs, Spinal-EPs, and MEPs were obtained, evoked potentials were recorded continuously during and after clamping of the aorta (30 min). Neurological outcome at 24 h was correlated with evoked potentials, and histopathological findings.Results:fifteen animals became paraplegic. MEPs were always abolished after clamping of the aorta while Spinal-EPs and SEPs remained. The sensory evoked potentials (SEPs and Spinal-EPs) were the least sensitive to spinal cord ischaemia, and their presence had no correlation with the final clinical status (50% of false negatives). This was consistent with histopathological examination that showed damage almost entirely confined to the anterior horn, while the dorsal columns were generally well preserved. High spine MEPs evoked by twitch stimulation was the best predictor of clinical outcome (0% of false negatives, 0% of false positives).Conclusions:SEPs and Spinal-EPs cannot be used as safe monitors of ischaemia of the spinal cord. High spine MEPs evoked by twitch stimulation was the most useful for real-time evaluation of spinal cord ischaemia, and the best predictor of neurologic outcome during reperfusion

Independent ferroelectric contributions and rare-earth-induced polarization reversal in multiferroic TbMn2O5

Three independent contributions to the magnetically induced spontaneous polarization of multiferroic TbMn2O5 are uniquely separated by optical second harmonic generation and an analysis in terms of Landau theory. Two of them are related to the magnetic Mn3+/4+ order and are independent of applied fields of up to 7 T. The third contribution is related to the long-range antiferromagnetic Tb3+ order. It shows a drastic decrease upon the application of a magnetic field and mediates the change of sign of the spontaneous electric polarization in TbMn2O5. The close relationship between the rare-earth long-range order and the non-linear optical properties points to isotropic Tb-Tb exchange and oxygen spin polarization as mechanism for this rare-earth induced ferroelectricity.Comment: 8 pages, 5 figure

Landau Theory of Domain Wall Magnetoelectricity

We calculate the exact analytical solution to the domain wall properties in a multiferroic system with two order parameters that are coupled bi-quadratically. This is then adapted to the case of a magnetoelectric multiferroic material such as BiFeO3, with a view to examine critically whether the domain walls can account for the enhancement of magnetization reported for thin films fo this material, in view of the correlation between increasing magnetization and increasing volume fraction of domain walls as films become thinner. The present analysis can be generalized to describe a class of magnetoelectric devices based upon domain walls rather than bulk properties.Comment: 9 pages, 4 figure

A zinc-doped endodontic cement facilitates functional mineralization and stress dissipation at the dentin surface

The purpose of this study was to evaluate nanohardness and viscoelastic behavior of dentin surfaces treated with two canal sealer cements for dentin remineralization. Dentin surfaces were subjected to: i) 37% phosphoric acid (PA) or ii) 0.5 M ethylenediaminetetraacetic acid (EDTA) conditioning prior to the application of two experimental hydroxyapatite-based cements, containing sodium hydroxide (calcypatite) or zinc oxide (oxipatite), respectively. Samples were stored in simulated body fluid during 24 h or 21 d. The intertubular and peritubular dentin were evaluated using a nanoindenter to assess nanohardness (Hi). The load/displacement responses were used for the nano-dynamic mechanical analysis to estimate complex modulus (E*) and tan delta (?). The modulus mapping was obtained by imposing a quasistatic force setpoint to which a sinusoidal force was superimposed. AFM imaging and FESEM analysis were performed. After 21 d of storage, dentin surfaces treated with EDTA+calcypatite, PA+calcypatite and EDTA+oxipatite showed viscoelastic discrepancies between peritubular and intertubular dentin, meaning a risk for cracking and breakdown of the surface. At both 24 h and 21 d, tan ? values at intertubular dentin treated with the four treatments performed similar. At 21 d time point, intertubular dentin treated with PA+oxipatite achieved the highest complex modulus and nanohardness, i.e., highest resistance to deformation and functional mineralization, among groups. Intertubular and peritubular dentin treated with PA+oxipatite showed similar values of tan ? after 21 d of storage. This produced a favorable dissipation of energy with minimal energy concentration, preserving the structural integrity at the dentin surface

Pretransitional phenomena in dilute crystals with first-order phase transition

Pretransitional phenomena at first-order phase transition in crystals diluted by 'neutral' impurities (analogue of nonmagnetic atoms in dilute magnets) are considered. It is shown that field dependence of order parameter becomes nonanalytical in the stability region of the ordered phase, while smeared jumps of thermodynamic parameters and anomalous (non-exponential) relaxation appear near transition temperature of pure crystal.Comment: 4 page

Hydroxyapatite-based cements induce different apatite formation in radicular dentin

Objectives. To investigate crystallinity and ultrastructure of the formed hydroxyapatite at radicular cervical and apical dentin after being treated with three different canal sealers. Methods. Cervical and apical root dentin surfaces were treated with two experimental hydroxyapatite-based sealers, containing sodium hydroxide (calcypatite) or zinc oxide (oxipatite) and an epoxy resin-based canal sealer (AH Plus); gutta-percha without sealer was included as control. Dentin surfaces were studied by X-ray diffraction and transmission electron microscopy through selected area diffraction and bright-field imaging after 24 h and 12 m of storage. Results. Root cervical dentin treated with calcypatite and oxipatite produced poor crystallinity of new minerals, wide amorphous phase and non-stoichiometry. Reflections at the 002 plane and the corresponding diffraction rings attained lower values in the Scherrer equation and the Scherrer-Wilson equation in samples treated with both HAp-based sealers than in specimens without sealer or with AH Plus. At root cervical dentin treated with calcypatite, shorter and wider crystallite size formations and lower crystals grain size were found, if compared to those encountered at oxipatite treated dentin. Oxipatite attained improved crystallographic atomic order and less structural variation in both distances and angles. Apical dentin treated with oxipatite attained preferred grain orientation with polycrystalline lattices. Significance. The immature crystallites formed in dentin treated with calcypatite and oxipatite will account for high hydroxyapatite solubility and remineralizing activity. New polycrystalline formations encountered in apical dentin treated with oxipatite may also produce high mechanical performance.This work was supported by the Ministry of Economy and Competitiveness (MINECO) and European Regional Development Fund (FEDER) Project MAT2017-85999-P

Gone with Ciclón del 16 in Underguater ciberpunk Cuba by Erick J. Mota

La novela Habana Underguater y los cuentos del universo Underguater, publicados por el autor cubano Erick J. Mota en la primera década del siglo XXI, reflejan una forma diferente de hacer ciencia ficción en Cuba, y proponen una reapropiación y modernización de los mitos y las culturas transculturadas locales y caribeñas, poniendo énfasis en las culturas y etnias de origen afrodescendiente. A través de un ciberpunk —con “i” latina— (pero no segregado el experimento al estilo ciberpunk), el universo Underguater reflexiona sobre el pasado, el presente y el futuro distópicos de la isla caribeña y se pone como ejemplo de las propuestas de muchos otros escritores del fantástico caribeño del siglo XXI.Together, the novel Havana Underguater and the short stories of the Underguater universe, published by Cuban author Erick J. Mota in the first decade of the 21st century, reflect a different way of writing science fiction in Cuba, and propose a re-appropriation and modernization of the—already transcultural—myths in the local and Caribbean societies, with special emphasis on those of African descent origin. Through a cyberpunk written with Latin i (but not limited to it), this Underguater universe reflects on the past, present and future dystopian possibilities on the Caribbean island, and joins the proposals of many others writers of the 21st century Caribbean fantastic