Frequency dynamics of gain-switched injection-locked semiconductor lasers

The frequency dynamics of gain-switched singlemode semiconductor lasers subject to optical injection is investigated. The requirements for low time jitter and reduced frequency chirp operation are studied as a function of the frequency mismatch between the master and slave lasers. Suppression of the power overshoot, typical during gain-switched operation, can be achieved for selected frequency detunings

Las doleritas toleiticas triasicas del sector SE de la Cordillera Ibérica : Petrología y Geoquímica

Las doleritas toleíticas aflorantes en diapiros triásicos del SE de la Cordillera Ibérica (Alfarp, Quesa y Lugar Nuevo de Fenollet, SE de Valencia) representan líquidos diferenciados (valores bajos en Ni, Cr y mg*) emplazados como sills, de escaso espesor, por debajo de sedimentos (arcillas, margas y yesos), poco consolidados, del límite Triásico superior-Hettangiense. Su composición mineral y geoquímica, con afinidad toleítica continental y similitud a MORB, evidencia el carácter menos diferenciado de las doleritas de Alfarp, respecto a las de Quesa, siendo las doleritas aflorantes en Fenollet las que presentan una composición más evolucionada. Estas doleritas son la expresión de un magmatismo poco profundo, asociado al inicio del rifting mesozoico, desarrollado en la zona de intersección del rift celtibérico y el borde NE del surco bético. Este magmatismo presenta claras diferencias respecto a las doleritas toleíticas, menos diferenciadas, de los dominios pirenaico y bético.The tholeiitic dolerites that crop out in three diapirs of the SE of the Iberian Chain (Alfarp, Quesa and Lugar Nuevo de Fenollet, Valencia), are the expression of evolved (iow Ni, Cr and mg* values) basic magmas, injected into poorly lithified sediments (iutites, marls and gypsum) which represent the Upper Triassic (Keuper facies)-Hettangian boundary, developing sills with reduced thickness. Their mineral and whole-rock geochemical compositions indicate a continental tholeiitic affinity and certain similarities to a MORB composition and, on the other hand, show that the Alfarp dolerites represent the less evolved compositions, whereas the Fenollet dolerites show a significantly greater differentiation. These rocks are the expression of a shallow magmatism, related to the initial stages of the mesozoic rifting that affected the intersection of the Celtiberian Rift with the Betic Graben. This magmatism is clearly different of the isochronous tholeiitic magmatism (dolerites) which crops out at the Pyrenees and [email protected]

From floodplain to aquatic sediments: Radiogeochronological fingerprints in a sediment core from the mining impacted Sancho Reservoir (SW Spain)

The Sancho Reservoir (SW Spain) was built in 1962, about the time of maximum 137Cs fallout, and it has been affected by acid mine drainage (AMD) particularly since the mining cease in 2001. This is a unique scenario for studying the radiogeochronological fingerprints in AMD-affected sediments deposited over the former flood plain. A sediment core sampled in 2011 was analysed for bulk density, 137Cs, 239Pu, 240Pu, 210Pb, 226Ra, 228Ra, 234Th (238U) and 40K, and studied with various radiometric dating models. Bulk density revealed unsteady compaction and likely depositional events. The activity concentrations of 226Ra, 228Ra, 234Th (238U) and 40K were uniform down-core, but declining overall in the upper 0–25 cm, revealing changes in provenance except for 238U, which increased in the top 10 cm likely due to its supply by AMD. The AMD fingerprint was also found in the 239+240Pu/137Cs activity ratio, which increased in the top sediment layers. The 137Cs and 239+240Pu profiles show well defined peaks at the same depth, with inventories being about four times higher than the expected integrated atmospheric deposition in the area. The unsupported 210Pb (210Pbexc) showed a complex non-monotonic profile interrupted at several sections, particularly around the 137Cs peak. The whole dataset cannot be interpreted in terms of continuous sedimentation processes. Based upon correlated features in the bulk density and 210Pbexc profiles, a series of depositional events (likely linked to peaks in the rainfall records) have been identified in the core. These events date back to the period comprised since the construction of the dam until its increase in height in 1972, which likely displaced upstream the main depositional area of riverine loads, as inferred from sediment trap data. The CRS (with a reference date) and (a piecewise) CIC models have been used for complementing and discussing the chronology.Ministerio de Economia y Competitividad CTM2015-68628-

Triassic tholeiitic dolerites («ophites») of the El Grado diapir (Pyrenees, Huesca, Spain): emplacement and composition

Mesozoic dolerites in the south Pyrenean sector of El Grado (Huesca, Spain) preserve emplacement structures (fluidity structures at the top and load structures at the base) developed during their intrusion into unconsolidated marly-evaporitic Triassic sediments (Keuper facies). By analogy with other dolerites in the south Pyrenean domain, their emplacement age is equivalent to the uppermost Keuper facies terms, but prior to the final Triassic-early Liassic carbonated sediments. Radiometric ages (187-197±7 Ma) show that the emplacement occurred during the lower Liassic. The petralogical differentiation from the chilled margin facies to the central facies, and also to the late pegmatitoids, is consistent with that obtained from major elements, trace elements and REE. Their tholeiitic affinity, as defined by their geochemical composition, is equivalent to that of similar racks in the Pyrenean domain. However, the rocks analyzed here, which are located at the external sector of this domain, display a greater petralogical and geochemical differentiation as compared to similar rocks in the central sectors of the Pyrenean domain.Las doleritas mesozoicas del sector surpirenaico de El Grado (Huesca) conservan estructuras de emplazamiento (con desarrollo del movimiento de lava fluida al techo y de carga en su base) desarrolladas al instruir en los sedimentos margo-evaporíticos en facies Keuper, todavía inconsolidados. Por similitud con otras doleritas del dominio surpirenaico, la edad del emplazamiento es equivalente a la de los términos superiores de la facies Keuper y previa a la sedimentación carbonatada del Trías terminal-Lías inferior. Las determinaciones de edades radiométricas (187-197±7 Ma) indican que el emplazamiento debió tener lugar durante el Lías inferior. La diferenciación petralógica, desde la facies del borde enfriado a la central y, también, al posterior diferenciado pegmatoide concuerda con la obtenida con elementos mayores, trazas y REE. Su afinidad toleítica, definida por su composición geoquímica, coincide con la obtenida en rocas análogas para el dominio pirenaico; no obstante, estas rocas situadas en el borde más externo de dicho dominio representan una mayor diferenciación (petralógica y geoquímica) respecto a la obtenida, hasta el momento, para rocas análogas situadas en sectores más centrales del citado dominio pirenaico

The triassic alkaline dolerites of the Valacloche-Camarena Area (SE-Iberian Chain, Teruel): Geodynamic implications

The dolerite sills outcropping in the Valacloche-Camarena area (SE Iberian Chain), are the expression of an alkaline magmatism, emplaced in Keuper facies sedimentary rocks. Their pre-Hettangian age is deduced from the development of fluidality structures at the top of the sills together with the very low grade contact metamorphism of the host rocks. A differentiation trend, represented by two rock-types, with variable Ti-augite content, is confirmed by geochemical data (REE). The alkaline composition of this magmatism is close to that of the OIB type. Crust-derived enclaves (metapelites and granitoids) are common in these sills, suggesting that magma ascent took place through a fracture system, related to a distensive tectonic regime, that affected different levels of the crust. This magmatism was one of the expressions of the triassic rifting events that are well represented in the SE border of the Iberian Chain.Un magmatismo alcalino, emplazado en sedimentos triásicos en facies Keuper, está bien representado en los sills doleríticos del área de Valacloche-Camarena (SE de la Cordillera Ibérica). La edad pre-Hettangiense ha sido deducida a partir de la presencia de estructuras de fluidalidad y de un metamorfismo de contacto de grado muy débil. Petrológicamente se identifica una fraccionación según dos litotipos (con contenido variable en Ti-augita) que está corroborada por los datos de composición geoquímica (en tierras raras); la composición alcalina de este magmatismo es próxima a la del tipo OIB. La presencia, frecuente, de enclaves de corteza (metapelitas y granitoides) indica una fracturación que, en condiciones distensivas, afectó a distintos niveles de dicha corteza. Este magmatismo está ligado al rifting triásico que está bien expresado en el borde SE de la Cordillera Ibérica

Frozen cancellous bone allografts: positive cultures of implanted grafts in posterior fusions of the spine

We have carried out a study on the behaviour pattern of implanted allografts initially stored in perfect conditions (aseptically processed, culture-negative and stored at -80 degrees C) but which presented positive cultures at the implantation stage. There is no information available on how to deal with this type of situation, so our aim was to set guidelines on the course of action which would be required in such a case. This was a retrospective study of 112 patients who underwent a spinal arthrodesis and in whom a total of 189 allograft pieces were used. All previous bone and blood cultures and tests for hepatitis B and C, syphilis and HIV (via PCR techniques) were negative. The allografts were stored by freezing them at -80 degrees C. A sample of the allograft was taken for culture in the operating theatre just before its implantation in all cases. The results of the cultures were obtained 3-5 days after the operation. There were 22 allografts with positive culture results (12%) after implantation. These allografts were implanted in 16 patients (14%). Cultures were positive for staphylococci coagulase negative (ECN) in 10 grafts (46%), Pseudomonas stutzeri in two grafts (9%), Corynebacterium jeikeium in two grafts (9%), staphylococci coagulase positive in two grafts (9%) and for each of the following organisms in one case each (4%): Corynebacterium spp., Actinomyces odontolyticus, Streptococcus mitis, Peptostreptococcus spp., Rhodococcus equi and Bacillus spp. No clinical infection was seen in any of these patients. Positive cultures could be caused by non-detected contamination at harvesting, storing or during manipulation before implantation. The lack of clinical signs of infection during the follow-up of our patients may indicate that no specific treatment different from our antibiotic protocol is required in the case of positive culture results of a graft piece after implantation

Resonant radiation pressure on neutral particles in a waveguide

A theoretical analysis of electromagnetic forces on neutral particles in an hollow waveguide is presented. We show that the effective scattering cross section of a very small (Rayleigh) particle can be strongly modified inside a waveguide. The coupling of the scattered dipolar field with the waveguide modes induce a resonant enhanced backscattering state of the scatterer-guide system close to the onset of new modes. The particle effective cross section can then be as large as the wavelength even far from any transition resonance. As we will show, a small particle can be strongly accelerated along the guide axis while being highly confined in a narrow zone of the cross section of the guide.Comment: RevTeX,4 pages,3 PS figure

¿Es una sabana nativa un sumidero de carbono? ¿Y cuáles son los cambios que se generan al convertirse en un pastizal?

Como parte de los cambios de uso del suelo en las tierras bajas del Orinoco, las sabanas han sido reemplazadas por Brachiaria. La pregunta que sigue sin respuesta es:¿cómo la sustitución de la vegetación nativa afecta el intercambio de CO2 en las escalas estacionales y anuales? Para evaluarlos intercambios de carbono, hemos determinado los flujos de CO2 por el método Eddy,y los flujos de CO2 del suelo. La dinámica fuente/sumidero del carbono en los dos doseles difiere notablemente. Mediciones anuales de la producción neta del ecosistema indican que Brachiaria constituyó un sumidero de carbono de 216gCm-2 año-1 Por el contrario,la sabana presentó un estado equilibrado de carbono(36 gCm-2 año-1). La respiración estacional del ecosistema estuvo linealmente relacionada con la producción estacional primaria bruta enuna proporción de 53%.La captación de carbono fue limitada por el contenido volumétrico de agua en el suelo como se reflejó en la eficiencia del uso del agua.After land use changes in the Orinoco lowlands, savannas have been replaced by Brachiaria pasture. Question that remain unanswered include: how do the replacement of the native vegetation affect the exchange of CO2 on the seasonal and annual course.To address the inquires, we determined the CO2 fluxes by eddy covariance and soil CO2 efflux system. The carbon source/sink dynamics over the two canopies differed markedly. Annual measurements of the Net Ecosystem Production indicated that the Brachiaria field was a carbon sink of 216 g C m- 2 y-1. However, this carbon accumulation by the ecosystem is trading for water losses. By contrast, the savanna stand presented a balanced carbon status (36 g C m-2 y-1).Seasonal ecosystem respiration was linearly related to seasonal gross primary production and the proportion of 53 percent. Carbon uptake was limited for the volumetric soil water content as reflected by the water use efficiency.Eje A4: Ambiente, Naturaleza y AgroecologíaFacultad de Ciencias Agrarias y Forestale

¿Es una sabana nativa un sumidero de carbono? ¿Y cuáles son los cambios que se generan al convertirse en un pastizal?

Como parte de los cambios de uso del suelo en las tierras bajas del Orinoco, las sabanas han sido reemplazadas por Brachiaria. La pregunta que sigue sin respuesta es:¿cómo la sustitución de la vegetación nativa afecta el intercambio de CO2 en las escalas estacionales y anuales? Para evaluarlos intercambios de carbono, hemos determinado los flujos de CO2 por el método Eddy,y los flujos de CO2 del suelo. La dinámica fuente/sumidero del carbono en los dos doseles difiere notablemente. Mediciones anuales de la producción neta del ecosistema indican que Brachiaria constituyó un sumidero de carbono de 216gCm-2 año-1 Por el contrario,la sabana presentó un estado equilibrado de carbono(36 gCm-2 año-1). La respiración estacional del ecosistema estuvo linealmente relacionada con la producción estacional primaria bruta enuna proporción de 53%.La captación de carbono fue limitada por el contenido volumétrico de agua en el suelo como se reflejó en la eficiencia del uso del agua.After land use changes in the Orinoco lowlands, savannas have been replaced by Brachiaria pasture. Question that remain unanswered include: how do the replacement of the native vegetation affect the exchange of CO2 on the seasonal and annual course.To address the inquires, we determined the CO2 fluxes by eddy covariance and soil CO2 efflux system. The carbon source/sink dynamics over the two canopies differed markedly. Annual measurements of the Net Ecosystem Production indicated that the Brachiaria field was a carbon sink of 216 g C m- 2 y-1. However, this carbon accumulation by the ecosystem is trading for water losses. By contrast, the savanna stand presented a balanced carbon status (36 g C m-2 y-1).Seasonal ecosystem respiration was linearly related to seasonal gross primary production and the proportion of 53 percent. Carbon uptake was limited for the volumetric soil water content as reflected by the water use efficiency.Eje A4: Ambiente, Naturaleza y AgroecologíaFacultad de Ciencias Agrarias y Forestale