Peccei--Quinn mechanism in gravity and the nature of the Barbero--Immirzi parameter

A general argument provides the motivation to consider the Barbero--Immirzi parameter as a field. The specific form of the geometrical effective action allows to relate the value of the Barbero--Immirzi parameter to other quantum ambiguities through the analog of the Peccei--Quinn mechanism.Comment: Accepted for publication on Phys. Rev. Let

Tomás Segovia: the Gift of the Essay

Se propone una lectura del ensayo en Tomás Segovia (Valencia 1927), considerado uno de los más altos exponentes y renovadores del género en lengua española. Se interpreta su obra ensayística a partir de las distintas connotaciones de la idea de “don” (gracia, maestría, reciprocidad). Lucidez y don de la palabra son dos de los rasgos que acompañan al ensayo de Segovia en el despliegue de una honda interpretación siempre guiada por la buena fe en la busca del sentido. Para Segovia el ensayo es el género moral por excelencia, es un espacio compartido de reflexión sobre el sentido y el valor, es invitación al diálogo, es responsabilidad por la palabra dicha, es exploración del lenguaje y representación del proceso mismo de pensar.The article offers a reading of the essay-writing of Tomás Segovia (Valencia, 1927), who is considered one of the most important exponents and renovators of the genre in Spanish. The study of his essays parts from the different connotations of the idea of "gift" (grace, mastery, recprocity). Lucidity and the gift of the word are two features which accompany Segovia's essay-writing in deep interpretations guided always by an honest search for meaning. For Segovia the essay is the moral genre par excellence, a shared space of reflection on meaning and value, and an invitation to dialogue; it is responsability for the spoken word, exploration of language and representation of thought processes

Statistical mechanics and the description of the early universe II. Principle of detailed balance and primordial 4He formation

If the universe is slightly non-extensive, and the distribution functions are not exactly given by those of Boltzmann-Gibbs, the primordial production of light elements will be non-trivially modified. In particular, the principle of detailed balance (PDB), of fundamental importance in the standard analytical analysis, is no longer valid, and a non-extensive correction appears. This correction is computed and its influence is studied and compared with previous works, where, even when the universe was considered as an slightly non-extensive system, the PDB was assumed valid. We analytically track the formation of Helium and Deuterium, and study the kind of deviation one could expect from the standard regime. The correction to the capture time, the moment in which Deuterium can no longer be substantially photo-disintegrated, is also presented. This allows us to take into account the process of the free decay of neutrons, which was absent in all previous treatments of the topic. We show that even when considering a first (linear) order correction in the quantum distribution functions, the final output on the primordial nucleosynthesis yields cannot be reduced to a linear correction in the abundances. We finally obtain new bounds upon the non-extensive parameter, both comparing the range of physical viability of the theory, and using the latest observational data.Comment: 24 pages, to appear in Physica A (2001

Engineering Escherichia coli to grow constitutively on D-xylose using the carbon-efficient Weimberg pathway

Bio-production of fuels and chemicals from lignocellulosic C5 sugars usually requires the use of the pentose phosphate pathway (PPP) to produce pyruvate. Unfortunately, the oxidation of pyruvate to acetyl-coenzyme A results in the loss of 33 % of the carbon as CO2, to the detriment of sustainability and process economics. To improve atom efficiency, we engineered Escherichia coli to utilize d-xylose constitutively using the Weimberg pathway, to allow direct production of 2-oxoglutarate without CO2 loss. After confirming enzyme expression in vitro, the pathway expression was optimized in vivo using a combinatorial approach, by screening a range of constitutive promoters whilst systematically varying the gene order. A PPP-deficient (ΔxylAB), 2-oxoglutarate auxotroph (Δicd) was used as the host strain, so that growth on d -xylose depended on the expression of the Weimberg pathway, and variants expressing Caulobacter crescentus xylXAB could be selected on minimal agar plates. The strains were isolated and high-throughput measurement of the growth rates on d-xylose was used to identify the fastest growing variant. This strain contained the pL promoter, with C. crescentus xylA at the first position in the synthetic operon, and grew at 42 % of the rate on d-xylose compared to wild-type E. coli using the PPP. Remarkably, the biomass yield was improved by 53.5 % compared with the wild-type upon restoration of icd activity. Therefore, the strain grows efficiently and constitutively on d-xylose, and offers great potential for use as a new host strain to engineer carbon-efficient production of fuels and chemicals via the Weimberg pathway

Stress tolerance mechanisms in Juncus: responses to salinity and drought in three Juncus species adapted to different natural environments

[EN] Comparative studies on the responses to salinity and drought were carried out in three Juncus species, two halophytes (Juncus maritimus Lam. and Juncus acutus L.) and one more salt-sensitive (Juncus articulatus L.). Salt tolerance in Juncus depends on the inhibition of transport of toxic ions to the aerial part. In the three taxa studied Na+ and Cl accumulated to the same extent in the roots of salt treated plants; however, ion contents were lower in the shoots and correlated with the relative salt sensitivity of the species, with the lowest levels measured in the halophytes. Activation of K+ transport at high salt concentration could also contribute to salt tolerance in the halophytes. Maintenance of cellular osmotic balance is mostly based on the accumulation of sucrose in the three species. Yet, neither the relative salt-induced increase in sugar content nor the absolute concentrations reached can explain the observed differences in salt tolerance. In contrast, proline increased significantly in the presence of salt only in the salt-tolerant J. maritimus and J. acutus, but not in J. articulatus. Similar patterns of osmolyte accumulation were observed in response to water stress, supporting a functional role of proline in stress tolerance mechanisms in JuncusThis work was partly funded by a grant to O.V. from the Spanish Ministry of Science and Innovation (Project CGL2008-00438/BOS), with contribution by the European Regional Development Fund. Mohamad Al Hassan was a recipient of an Erasmus Mundus pre-doctoral scholarship financed by the European Commission (Welcome Consortium)Al Hassan, M.; López Gresa, MP.; Boscaiu Neagu, MT.; Vicente Meana, Ó. (2016). Stress tolerance mechanisms in Juncus: responses to salinity and drought in three Juncus species adapted to different natural environments. FUNCTIONAL PLANT BIOLOGY. 43:949-960. https://doi.org/10.1071/FP16007S94996043Al Hassan, M., Chaura, J., López-Gresa, M. P., Borsai, O., Daniso, E., Donat-Torres, M. P., … Boscaiu, M. (2016). Native-Invasive Plants vs. Halophytes in Mediterranean Salt Marshes: Stress Tolerance Mechanisms in Two Related Species. Frontiers in Plant Science, 7. doi:10.3389/fpls.2016.00473Albert, R., & Popp, M. (1977). Chemical composition of halophytes from the Neusiedler Lake region in Austria. Oecologia, 27(2), 157-170. doi:10.1007/bf00345820Ashraf, M., & Foolad, M. R. (2007). Roles of glycine betaine and proline in improving plant abiotic stress resistance. Environmental and Experimental Botany, 59(2), 206-216. doi:10.1016/j.envexpbot.2005.12.006Bartels, D., & Sunkar, R. (2005). Drought and Salt Tolerance in Plants. Critical Reviews in Plant Sciences, 24(1), 23-58. doi:10.1080/07352680590910410Bates, L. S., Waldren, R. P., & Teare, I. D. (1973). Rapid determination of free proline for water-stress studies. Plant and Soil, 39(1), 205-207. doi:10.1007/bf00018060Boscaiu, M., Ballesteros, G., Naranjo, M. A., Vicente, O., & Boira, H. (2011). Responses to salt stress in Juncus acutus and J. maritimus during seed germination and vegetative plant growth. Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 145(4), 770-777. doi:10.1080/11263504.2011.628446Boscaiu, M., Lull, C., Llinares, J., Vicente, O., & Boira, H. (2012). Proline as a biochemical marker in relation to the ecology of two halophytic Juncus species. Journal of Plant Ecology, 6(2), 177-186. doi:10.1093/jpe/rts017Bose, J., Rodrigo-Moreno, A., & Shabala, S. (2013). ROS homeostasis in halophytes in the context of salinity stress tolerance. Journal of Experimental Botany, 65(5), 1241-1257. doi:10.1093/jxb/ert430Boyer, J. S. (1982). Plant Productivity and Environment. Science, 218(4571), 443-448. doi:10.1126/science.218.4571.443Chen, T. H. H., & Murata, N. (2008). Glycinebetaine: an effective protectant against abiotic stress in plants. Trends in Plant Science, 13(9), 499-505. doi:10.1016/j.tplants.2008.06.007Clarke, L. D., & Hannon, N. J. (1970). The Mangrove Swamp and Salt Marsh Communities of the Sydney District: III. Plant Growth in Relation to Salinity and Waterlogging. The Journal of Ecology, 58(2), 351. doi:10.2307/2258276Drabkova, L., Kirschner, J., & Vlcek, C. (2006). Phylogenetic relationships within Luzula DC. and Juncus L. (Juncaceae): A comparison of phylogenetic signals of trnL-trnF intergenic spacer, trnL intron and rbcL plastome sequence data. Cladistics, 22(2), 132-143. doi:10.1111/j.1096-0031.2006.00095.xDuBois, M., Gilles, K. A., Hamilton, J. K., Rebers, P. A., & Smith, F. (1956). Colorimetric Method for Determination of Sugars and Related Substances. Analytical Chemistry, 28(3), 350-356. doi:10.1021/ac60111a017Espinar, J. L., Garcia, L. V., & Clemente, L. (2005). Seed storage conditions change the germination pattern of clonal growth plants in Mediterranean salt marshes. American Journal of Botany, 92(7), 1094-1101. doi:10.3732/ajb.92.7.1094Espinar, J. L., García, L. V., Figuerola, J., Green, A. J., & Clemente, L. (2006). Effects of salinity and ingestion by ducks on germination patterns of Juncus subulatus seeds. Journal of Arid Environments, 66(2), 376-383. doi:10.1016/j.jaridenv.2005.11.001Fita, A., Rodríguez-Burruezo, A., Boscaiu, M., Prohens, J., & Vicente, O. (2015). Breeding and Domesticating Crops Adapted to Drought and Salinity: A New Paradigm for Increasing Food Production. Frontiers in Plant Science, 6. doi:10.3389/fpls.2015.00978Flowers, T. J., & Colmer, T. D. (2008). Salinity tolerance in halophytes*. New Phytologist, 179(4), 945-963. doi:10.1111/j.1469-8137.2008.02531.xFlowers, T. J., Hajibagheri, M. A., & Clipson, N. J. W. (1986). Halophytes. The Quarterly Review of Biology, 61(3), 313-337. doi:10.1086/415032Flowers, T. J., Munns, R., & Colmer, T. D. (2014). Sodium chloride toxicity and the cellular basis of salt tolerance in halophytes. Annals of Botany, 115(3), 419-431. doi:10.1093/aob/mcu217Gagneul, D., Aïnouche, A., Duhazé, C., Lugan, R., Larher, F. R., & Bouchereau, A. (2007). A Reassessment of the Function of the So-Called Compatible Solutes in the Halophytic Plumbaginaceae Limonium latifolium. Plant Physiology, 144(3), 1598-1611. doi:10.1104/pp.107.099820GIL, R., LULL, C., BOSCAIU, M., BAUTISTA, I., LIDÓN, A., & VICENTE, O. (2011). Soluble Carbohydrates as Osmolytes in Several Halophytes from a Mediterranean Salt Marsh. Notulae Botanicae Horti Agrobotanici Cluj-Napoca, 39(2), 09. doi:10.15835/nbha3927176Gil, R., Boscaiu, M., Lull, C., Bautista, I., Lidón, A., & Vicente, O. (2013). Are soluble carbohydrates ecologically relevant for salt tolerance in halophytes? Functional Plant Biology, 40(9), 805. doi:10.1071/fp12359Gil, R., Bautista, I., Boscaiu, M., Lidon, A., Wankhade, S., Sanchez, H., … Vicente, O. (2014). Responses of five Mediterranean halophytes to seasonal changes in environmental conditions. AoB PLANTS, 6(0), plu049-plu049. doi:10.1093/aobpla/plu049Glenn, E. (1999). Salt Tolerance and Crop Potential of Halophytes. Critical Reviews in Plant Sciences, 18(2), 227-255. doi:10.1016/s0735-2689(99)00388-3GORHAM, J., HUGHES, L., & WYN JONES, R. G. (2006). Chemical composition of salt-marsh plants from Ynys Môn (Anglesey): the concept of physiotypes. Plant, Cell & Environment, 3(5), 309-318. doi:10.1111/1365-3040.ep11581858Grieve, C. M., & Grattan, S. R. (1983). Rapid assay for determination of water soluble quaternary ammonium compounds. Plant and Soil, 70(2), 303-307. doi:10.1007/bf02374789Gupta, B., & Huang, B. (2014). Mechanism of Salinity Tolerance in Plants: Physiological, Biochemical, and Molecular Characterization. International Journal of Genomics, 2014, 1-18. doi:10.1155/2014/701596Hamamoto, S., Horie, T., Hauser, F., Deinlein, U., Schroeder, J. I., & Uozumi, N. (2015). HKT transporters mediate salt stress resistance in plants: from structure and function to the field. Current Opinion in Biotechnology, 32, 113-120. doi:10.1016/j.copbio.2014.11.025Hariadi, Y., Marandon, K., Tian, Y., Jacobsen, S.-E., & Shabala, S. (2010). Ionic and osmotic relations in quinoa (Chenopodium quinoa Willd.) plants grown at various salinity levels. Journal of Experimental Botany, 62(1), 185-193. doi:10.1093/jxb/erq257Jones, E., Simpson, D., Hodkinson, T., Chase, M., & Parnell, J. (2007). The Juncaceae-Cyperaceae Interface: A Combined Plastid Sequence Analysis. Aliso, 23(1), 55-61. doi:10.5642/aliso.20072301.07Kumari, A., Das, P., Parida, A. K., & Agarwal, P. K. (2015). Proteomics, metabolomics, and ionomics perspectives of salinity tolerance in halophytes. Frontiers in Plant Science, 6. doi:10.3389/fpls.2015.00537Munns, R., & Termaat, A. (1986). Whole-Plant Responses to Salinity. Functional Plant Biology, 13(1), 143. doi:10.1071/pp9860143Munns, R., & Tester, M. (2008). Mechanisms of Salinity Tolerance. Annual Review of Plant Biology, 59(1), 651-681. doi:10.1146/annurev.arplant.59.032607.092911Naidoo, G., & Kift, J. (2006). Responses of the saltmarsh rush Juncus kraussii to salinity and waterlogging. Aquatic Botany, 84(3), 217-225. doi:10.1016/j.aquabot.2005.10.002Niu, X., Bressan, R. A., Hasegawa, P. M., & Pardo, J. M. (1995). Ion Homeostasis in NaCl Stress Environments. Plant Physiology, 109(3), 735-742. doi:10.1104/pp.109.3.735Ozgur, R., Uzilday, B., Sekmen, A. H., & Turkan, I. (2013). Reactive oxygen species regulation and antioxidant defence in halophytes. Functional Plant Biology, 40(9), 832. doi:10.1071/fp12389Pang, Q., Chen, S., Dai, S., Chen, Y., Wang, Y., & Yan, X. (2010). Comparative Proteomics of Salt Tolerance inArabidopsis thalianaandThellungiella halophila. Journal of Proteome Research, 9(5), 2584-2599. doi:10.1021/pr100034fPartridge, T. R., & Wilson, J. B. (1987). Salt tolerance of salt marsh plants of Otago, New Zealand. New Zealand Journal of Botany, 25(4), 559-566. doi:10.1080/0028825x.1987.10410086RAVEN, J. A. (1985). TANSLEY REVIEW No. 2. REGULATION OF PH AND GENERATION OF OSMOLARITY IN VASCULAR PLANTS: A COST-BENEFIT ANALYSIS IN RELATION TO EFFICIENCY OF USE OF ENERGY, NITROGEN AND WATER. New Phytologist, 101(1), 25-77. doi:10.1111/j.1469-8137.1985.tb02816.xRodrı́guez-Navarro, A. (2000). Potassium transport in fungi and plants. Biochimica et Biophysica Acta (BBA) - Reviews on Biomembranes, 1469(1), 1-30. doi:10.1016/s0304-4157(99)00013-1Rozema, J. (1976). An Ecophysiological Study on the Response to Salt of Four Halophytic and Glycophytic Juncus Species. Flora, 165(2), 197-209. doi:10.1016/s0367-2530(17)31845-5Rozema, J. (1991). Growth, water and ion relationships of halophytic monocotyledonae and dicotyledonae; a unified concept. Aquatic Botany, 39(1-2), 17-33. doi:10.1016/0304-3770(91)90019-2Smirnoff, N., & Cumbes, Q. J. (1989). Hydroxyl radical scavenging activity of compatible solutes. 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Memorias Seminario: Formación profesional: fundamento para la productividad y competitividad en el nuevo milenio

El SENA, en cumplimiento de su Misión Institucional, convocó a los más actualizados, autorizados y proactivos protagonistas e impulsores de los cambios metodológicos y orientadores de las modernas Instituciones de formación profesional en Latinoamérica y España, con el claro propósito de sensibilizar sobre la necesidad del cambio, de dinamizar Instituciones, procesos y procedimientos que procuren las acciones propias y coherentes con el momento actual y futuro que debemos afrontar.SENA, in fulfillment of its Institutional Mission, convened the most up-to-date, authorized and proactive protagonists and drivers of the methodological and guiding changes of modern Vocational Training Institutions in Latin America and Spain, with the clear purpose of raising awareness of the need for change, to energize institutions, processes and procedures that seek our own actions and consistent with the current and future moment we must face.Saludo institucional de bienvenida / Tulio Arbeláez Gómez -- La formación profesional como instrumento de cambio socio-económico / Gina Magnolia Riaño Barón -- Aproximaciones al tema de la fomación profesional en Colombia -- Visión de la ANDI sobre el sistema de formación profesional / Luis Carlos Villegas -- Visión de los trabajadores sobre el sistema de formación profesional / Luis Eduardo Garzón -- Visión prospectiva y desarrollos de la formación profesional en Colombia / Jaime Ramírez Guerrero -- Nuevas s endas de la fonnación profesional: una mirada internacional -- Nuevos enfoques para la formación profesional desde la perspectiva del BID / Claudio de Moura Castro -- Tendencias de la formación profesional en América Latina / Pedro D. Weimberg -- Formación profesional en los escenarios laboral y educativo: la experiencia española -- Dialogo social y formación profesional en el país Vasco / Javier Retegui Ayastuy -- Modelos o experiencias de la formación continua en España / Blanca Gómez Manzaneque -- Modelo para la implementación de la formación profesional ocupacional / Juan Bonet Tomás -- De las competencias laborales y su incidencia en el diseño y desarrollo de la formación profesional -- Normalización y certificación por competencias / Agustín Ibarra Almada -- Modelo de formación por competencias / Leonard Mertens -- Formación profesional en los escenarios laboral y educativo: la experiencia latinoamericana -- Formación y relaciones laborales / Oscar Hermida Uriarte -- Formación profesional y desarrollo tecnológico -- Experiencia de reestructuración en instituciones de formación profesional / Fernando Casanova -- Proyecto de modernización: la formación profesional fundamento central de una política social / Tulio Arbeláez Gómez -- Evaluación y conclusiones Seminario formación profesional Gonzalo Veléz Villegas.na303 página

Effects of Salt Stress on Three Ecologically Distinct Plantago Species

Comparative studies on the responses to salt stress of taxonomically related taxa should help to elucidate relevant mechanisms of stress tolerance in plants. We have applied this strategy to three Plantago species adapted to different natural habitats, P. crassifolia and P. coronopus both halophytes and P. major, considered as salt-sensitive since it is never found in natural saline habitats. Growth inhibition measurements in controlled salt treatments indicated, however, that P. major is quite resistant to salt stress, although less than its halophytic congeners. The contents of monovalent ions and specific osmolytes were determined in plant leaves after four-week salt treatments. Salt-treated plants of the three taxa accumulated Na+ and Cl- in response to increasing external NaCl concentrations, to a lesser extent in P. major than in the halophytes; the latter species also showed higher ion contents in the non-stressed plants. In the halophytes, K+ concentration decreased at moderate salinity levels, to increase again under high salt conditions, whereas in P. major K+ contents were reduced only above 400 mM NaCl. Sorbitol contents augmented in all plants, roughly in parallel with increasing salinity, but the relative increments and the absolute values reached did not differ much in the three taxa. On the contrary, a strong (relative) accumulation of proline in response to high salt concentrations (600 800 mM NaCl) was observed in the halophytes, but not in P. major. These results indicate that the responses to salt stress triggered specifically in the halophytes, and therefore the most relevant for tolerance in the genus Plantago are: a higher efficiency in the transport of toxic ions to the leaves, the capacity to use inorganic ions as osmotica, even under low salinity conditions, and the activation, in response to very high salt concentrations, of proline accumulation and K+ transport to the leaves of the plants.MAH was a recipient of an Erasmus Mundus pre-doctoral scholarship financed by the European Commission (Welcome Consortium). AP acknowledges the Erasmus mobility programme for funding her stay in Valencia to carry out her Master Thesis.Al Hassan, M.; Pacurar, AM.; López Gresa, MP.; Donat Torres, MDP.; Llinares Palacios, JV.; Boscaiu Neagu, MT.; Vicente Meana, Ó. (2016). Effects of Salt Stress on Three Ecologically Distinct Plantago Species. PLoS ONE. 11(8):1-21. doi:10.1371/journal.pone.0160236S12111