Nonlinear Propagation of Crossing Electromagnetic Waves in Vacuum due to Photon-Photon Scattering

We review the theory for photon-photon scattering in vacuum, and some of the proposals for its experimental search, including the results of our recent works on the subject. We then describe a very simple and sensitive proposal of an experiment and discuss how it can be used at the present (HERCULES) and the future (ELI) ultrahigh power laser facilities either to find the first evidence of photon-photon scattering in vacuum, or to significantly improve the current experimental limits.Comment: Talk delivered (by D.T.) at the International Workshop on the Frontiers of Modern Plasma Physics, Trieste, 2008. To appear in the proceeding

Nonlinear phase shift from photon-photon scattering in vacuum

We show that QED nonlinear effects imply a phase correction to the linear evolution of electromagnetic waves in vacuum. We provide explicit solutions of the modified Maxwell's equations for the propagation of a superposition of two plane waves, and calculate analytically and numerically the corresponding phase shift. This provides a new framework for the search of all-optical signatures of photon-photon scattering in vacuum. In particular, we propose an experiment for measuring the phase shift in projected high-power laser facilities.Comment: 4 pages, 1 figure. Some references were added, and the comparison with AC Kerr effect has been improve

Detecting photon-photon scattering in vacuum at exawatt lasers

In a recent paper, we have shown that the QED nonlinear corrections imply a phase correction to the linear evolution of crossing electromagnetic waves in vacuum. Here, we provide a more complete analysis, including a full numerical solution of the QED nonlinear wave equations for short-distance propagation in a symmetric configuration. The excellent agreement of such a solution with the result that we obtain using our perturbatively-motivated Variational Approach is then used to justify an analytical approximation that can be applied in a more general case. This allows us to find the most promising configuration for the search of photon-photon scattering in optics experiments. In particular, we show that our previous requirement of phase coherence between the two crossing beams can be released. We then propose a very simple experiment that can be performed at future exawatt laser facilities, such as ELI, by bombarding a low power laser beam with the exawatt bump.Comment: 8 pages, 6 figure

Oil spill effects on macrofaunal communities and bioturbation of pristine marine sediments (Caleta Valdés, Patagonia, Argentina): experimental evidence of low resistance capacities of benthic systems without history of pollution

The Patagonian coast is characterized by the existence of pristine ecosystems which may be particularly sensitive to oil contamination. In this study, a simulated oil spill at acute and chronic input levels was carried out to assess the effects of contamination on the macrobenthic community structure and the bioturbation activity of sediments sampled in Caleta Valdés creek. Superficial sediments were either noncontaminated or contaminated by Escalante crude oil and incubated in the laboratory for 30 days. Oil contamination induced adverse effects on macrobenthic community at both concentrations with, for the highest concentration, a marked decrease of approximately 40 and 55%of density and specific richness, respectively. Besides the disappearance of sensitive species, some other species like Oligochaeta sp. 1, Paranebalia sp., and Ostracoda sp. 2 species have a higher resistance to oil contamination. Sediment reworking activity was also affected by oil addition. At the highest level of contamination, nearly no activity was observed due to the high mortality of macroorganisms. The results strongly suggest that an oil spill in this protected marine area with no previous history of contamination would have a deep impact on the non-adapted macrobenthic community

Evidence of Paraoxonases 1, 2, and 3 Expression in Human Ovarian Granulosa Cells

Increasing evidence suggests that the antioxidant paraoxonase proteins, PON1, PON2, and PON3, have a role in reproduction and may be synthesized by ovarian cells. The aim of this work was to investigate whether human ovarian granulosa cells (GC) express paraoxonases 1, 2, and 3 (PON1, PON2, and PON3) at both the transcriptional and protein levels. Cells were purified from follicle samples of women undergoing ovarian stimulation at oocyte retrieval. We analyzed mRNA by polymerase chain reaction using specific primers for the different variants and quantified the proteins by Western blot using commercially available human recombinant PON proteins as standards. The protein subcellular distribution was determined by immunofluorescence and confocal microscopy and the cell cycles by flow cytometry. Thymidine was used for cellular synchronization at G1/S. Human hepatoma HepG2 and immortalized granulosa COV434 cell lines were used to optimize methodologies. mRNAs from PON1, the two variants of PON2, and PON3 were detected in GC. The cells actively secreted PON1 and PON3, as evidenced by the protein detection in the incubation medium. PON1 and PON3 were mainly distributed in the cytoplasm and notably in the nucleus, while PON2 colocalized with mitochondria. Subcellular nucleo-cytoplasmic distribution of PON1 was associated with the cell cycle. This is the first evidence describing the presence of mRNAs and proteins of the three members of the PON family in human ovarian GC. This study provides the basis of further research to understand the role of these proteins in GC, which will contribute to a better understanding of the reproduction process.This work was supported by research grants from the University of the Basque Country UPV/EHU (General Support to Research Groups, refs. GIU16/62 and GIU20/021), and Basque Government (pre-doctoral grant to I.P.-R.)

Métodos de transfección en macrófagos peritoneales de ratones ApoE K.O.

Este estudio pretende lograr la expresión transitoria de genes en macrófagos peritoneales de ratones knockout para la apoliproteína E (ApoE –) bajo la regulación de un promotor especifico de macrófagos. Para ello se clonó en un plásmido la región promotora del gen Cd68 murino, que codifica una glicoproteína específica de monocitos y macrófagos; seguido del gen Pon3 murino, que codifica una proteína con actividad lactonasa y función antioxidante; y el gen reportero luc de la luciérnaga oriental, que codifica la proteína luciferasa.El clonaje de la región promotora se abordó siguiendo dos estrategias distintas: una basada en la recombinación de secuencias homólogas y otra basada en la ligación de secuencias con extremos compatibles. Posteriormente se realizó la transfección de macrófagos peritoneales con el plásmido pCd68.Pon3.luc utilizando diferentes reactivos basados en dos métodos: transfección mediante liposomas o lipofección y transfección dirigida al núcleo mediante un campo eléctrico o electroporación.La sobreexpresión del plásmido se comprobó mediante medición de la actividad luciferasa, fosfatasa alcalina y proteína verde fluorescente.<br /

Internal Numerical Simulation of a Swirl Simplex Atomizer to Predict Atomization Outputs

International audienc

Reseñas

Ignacio Echevarría, Trayecto. Un recorrido crítico por la reciente narrativaespañola. Barcelona: Debate, 2005. Piña-Rosales, Gerardo, ed. Odón Betanzos Palacios o la integridad del árbolherido. Nueva York: Círculo de Escritores y Poetas Iberoamericanos de NuevaYork, 2005. 595. Raquel Macciuci y Natalia Corbellini, eds. De la periferia al centro. Discursode la “otredad” en la narrativa española contemporánea. La Plata: AlMargen, 2006. Brad Epps y Luis Fernández Cifuentes, eds. Spain Beyond Spain. Modernity,Literary History, and National Identity. Lewisburg: Bucknell University Press,2005. 388 páginas. Inmaculada Pertusa Seva. La salida del armario. Lecturas desde la otra acera.Gijón: Libros del Pexe, 2005.Ignacio Echevarría, Trayecto. Un recorrido crítico por la reciente narrativaespañola. Barcelona: Debate, 2005. Piña-Rosales, Gerardo, ed. Odón Betanzos Palacios o la integridad del árbolherido. Nueva York: Círculo de Escritores y Poetas Iberoamericanos de NuevaYork, 2005. 595. Raquel Macciuci y Natalia Corbellini, eds. De la periferia al centro. Discursode la “otredad” en la narrativa española contemporánea. La Plata: AlMargen, 2006. Brad Epps y Luis Fernández Cifuentes, eds. Spain Beyond Spain. Modernity,Literary History, and National Identity. Lewisburg: Bucknell University Press,2005. 388 páginas. Inmaculada Pertusa Seva. La salida del armario. Lecturas desde la otra acera.Gijón: Libros del Pexe, 2005. &nbsp

Analysis of Protein Oxidative Modifications in Follicular Fluid from Fertile Women: Natural Versus Stimulated Cycles

Oxidative stress is associated with obstetric complications during ovarian hyperstimulation in women undergoing in vitro fertilization. The follicular fluid contains high levels of proteins, which are the main targets of free radicals. The aim of this work was to determine specific biomarkers of non-enzymatic oxidative modifications of proteins from follicular fluid in vivo, and the effect of ovarian stimulation with gonadotropins on these biomarkers. For this purpose, 27 fertile women underwent both a natural and a stimulated cycle. The biomarkers, glutamic semialdehyde (GSA), aminoadipic semialdehyde (AASA), N-epsilon-(carboxymethyl)lysine (CML), and N-epsilon-(carboxyethyl)lysine (CEL), were measured by gas-liquid chromatography coupled to mass spectrometry. Results showed that follicular fluid contained products of protein modifications by direct metal-catalyzed oxidation (GSA and AASA), glycoxidation (CML and CEL), and lipoxidation (CML). GSA was the most abundant biomarker (91.5%). The levels of CML amounted to 6% of the total lesions and were higher than AASA (1.3%) and CEL (1.2%). In the natural cycle, CEL was significantly lower (p < 0.05) than in the stimulated cycle, suggesting that natural cycles are more protected against protein glycoxidation. These findings are the basis for further research to elucidate the possible relevance of this follicular biomarker of advanced glycation end product in fertility programs.This research was funded by the Basque Government, Department of Education, Universities and Research (project ref. IT687-13 and predoctoral grant to I.P.) and Department of Economic Development and Competitiveness, SPRI (refs. IG-20130001214 and IG-2014 0000837), University of the Basque Country UPV/EHU (ref. GIU16/62), and Fundacion Jesus Gangoiti (grant to S.M.)

Reseñas

Ignacio Echevarría, Trayecto. Un recorrido crítico por la reciente narrativa española. Barcelona: Debate, 2005. Piña-Rosales, Gerardo, ed. Odón Betanzos Palacios o la integridad del árbol herido. Nueva York: Círculo de Escritores y Poetas Iberoamericanos de Nueva York, 2005. 595. Raquel Macciuci y Natalia Corbellini, eds. De la periferia al centro. Discurso de la “otredad” en la narrativa española contemporánea. La Plata: Al Margen, 2006. Brad Epps y Luis Fernández Cifuentes, eds. Spain Beyond Spain. Modernity, Literary History, and National Identity. Lewisburg: Bucknell University Press, 2005. 388 páginas. Inmaculada Pertusa Seva. La salida del armario. Lecturas desde la otra acera. Gijón: Libros del Pexe, 2005.