Light in scattering media: active control and the exploration of intensity correlations

When light encounters scattering materials such as biological tissue, white paint or clouds, it gets randomly scattered in all directions, which traditionally has been seen as a barrier for imaging techniques (reducing their resolution) or sensing, due to the reduction of the penetration depth of light. However, in recent years it has been shown that scattering might not necessarily be an impediment, and that the knowledge of the properties of multiple scattering can be indeed useful for imaging, sensing and other applications. In the first part of this thesis (Chapters 2 to 5) we study the implications of manipulating the light incident on a multiply scattering material. We experimentally show how by actively controlling the output light of a bad quality laser we manage to not only improve its beam quality, but also in an energy-efficient way, in comparison with traditional methods. In a different experiment presented in this thesis, we show how the active control of the light incident on a scattering material can be useful to improve sensing through scattering media, by means of increasing the transmission and energy deposited inside (Chapter 5). In the final part of the thesis we present the first experimental observation of intensity correla- tions between transmitted and reflected patterns from a scattering material (Chapter 6), exploring how it depends on the parameters of the scattering medium. In the last part of the thesis (Chapter 7) we present a new imaging technique based on the use of the intensity correlations described in the previous chapter, opening new possibilities to non-invasive imaging through highly scattering materials

Correlations between reflected and transmitted intensity patterns emerging from opaque disordered media

The propagation of monochromatic light through a scattering medium produces speckle patterns in reflection and transmission, and the apparent randomness of these patterns prevents direct imaging through thick turbid media. Yet, since elastic multiple scattering is fundamentally a linear and deterministic process, information is not lost but distributed among many degrees of freedom that can be resolved and manipulated. Here we demonstrate experimentally that the reflected and transmitted speckle patterns are correlated, even for opaque media with thickness much larger than the transport mean free path, proving that information survives the multiple scattering process and can be recovered. The existence of mutual information between the two sides of a scattering medium opens up new possibilities for the control of transmitted light without any feedback from the target side, but using only information gathered from the reflected speckle.Comment: 6 pages, 4 figure

Blind Ghost Imaging

Ghost imaging is an unconventional optical imaging technique that reconstructs the shape of an object combining the measurement of two signals: one that interacted with the object, but without any spatial information, the other containing spatial information, but that never interacted with the object. Ghost imaging is a very flexible technique, that has been generalized to the single-photon regime, to the time domain, to infrared and terahertz frequencies, and many more conditions. Here we demonstrate that ghost imaging can be performed without ever knowing the patterns illuminating the object, but using patterns correlated with them, doesn't matter how weakly. As an experimental proof we exploit the recently discovered correlation between the reflected and transmitted light from a scattering layer, and reconstruct the image of an object hidden behind a scattering layer using only the reflected light, which never interacts with the object. This method opens new perspectives for non-invasive imaging behind or within turbid media.Comment: 5 pages, 4 figure

The exotic weevil Stenopelmus rufinasus Gyllenhal, 1835 (Coleoptera: Curculionidae) across a "host-free" pond network

The presence of the exotic weevil Stenopelmus rufinasus (Coleoptera: Curculionidae) is closely related to the occurrence of the exotic red water fern, Azolla filiculoides. In this paper, we present the first records of S. rufinasus in Doñana National Park (SW Spain), based on sampling of macroinvertebrates in 91 temporary ponds, including monthly samples of 22 ponds, during two successive years (2005-2007). The exotic weevil was present in 21% of the sampled ponds where the host plant, A. filiculiodes, was not detectable. Because A. filiculoides can reach high densities in an adjacent area of marsh, we suggest that the occurrence of the exotic weevil in these ponds is a consequence of dispersal from nearby marshes. Our study demonstrates that S. rufinasus adults can occur at relatively high densities in ponds where the host plant is not present, suggesting that such apparently “host-free” sites may act as stepping stones for the spread of this speciesLa presencia de la especie de gorgojo exótico Stenopelmus rufinasus (Coleoptera: Curculionidae) está íntimamente rela- cionada con la planta acuática exótica Azolla filiculoides. En este estudio se registró por primera vez la presencia de S. rufinasus en el Parque Nacional de Doñana (SO España) tras realizar un muestreo de macroinvertebrados en 91 lagunas que incluye muestreos mensuales de 22 de las mismas durante dos años consecutivos (2005-2007). El gorgojo exótico estuvo presente en el 21% de las lagunas muestreadas a pesar de que su supuesto hospedador, A. filiculiodes, no fue detectado. Dado que A. filiculiodes puede alcanzar grandes densidades en la marisma adyacente, sugerimos que la presencia del gor- gojo exótico en las lagunas temporales se debe a su dispersión desde la marisma. Este estudio demuestra que individuos adultos de S. rufinasus pueden aparecer con densidades relativamente altas en lagunas donde su hospedador potencial no está presente, lo que sugiere que estos sitios libres de hospedador podrían actuar como zonas de paso para la dispersión de la especiePeer reviewe

Prédation des oeufs et des larves d’amphibiens dans les mares temporaires: le cas de Bufo calamita dans le sud-ouest de l’Espagne

Eggs and larvae of bufonids are often unpalatable or toxic. We assessed the vulnerability of Bufo calamita eggs and larvae to nine potential predators. Ingestion did not exert toxic or distasteful effects on most predators, but small predators had difficulties extracting eggs from the jelly. In laboratory, the most intensive predation was by larvae of Sharp-ribbed Salamander Pleurodeles waltl (Amphibia, Salamandridae), the common crustacean Triops cancriformis (Crustacea Notostraca) and the introduced Red Swamp Crayfish Procambarus clarkii (Decapodes, Cambaridae). Predation rate was related to the body size of predators. Predation in breeding ponds reached up to 95-100% eggs, and breeding success was only recorded in ponds without the three major predators above. While other species of Bufo that contain toxic substances are able to colonize permanent aquatic habitats, for Bufo calamita only the compact jelly of eggs serves to deter small predatorsLes oeufs et les larves des bufonidés sont souvent désagréables ou toxiques. Nous avons évalué la vulnérabilité des oeufs et des larves de Bufo calamita face à neuf prédateurs potentiels. L'ingestion n'a pas exercé d'effets toxiques ou désagréables sur la plupart des prédateurs, en revanche les petits prédateurs ont eu des difficultés pour extraire les oeufs de la gélatine. Au laboratoire, les prédations les plus importantes ont été exercées par les larves de Pleurodèles de Waltl Pleurodeles waltl (Amphibiens, Salamandridés), les Triops Triops cancriformis (Crustacés Notostracés) et les Ecrevisses de Louisiane Procambarus clarkii (Décapodes, Cambaridés), espèce introduite. Le taux de prédation est lié à la taille des prédateurs. La prédation dans les mares de reproduction a affecté jusqu'à 95-100% des pontes, et le succès reproducteur n'a été constaté que dans les mares où ces trois prédateurs principaux sont absents. Tandis que d'autres espèces de Bufo, qui contiennent des substances toxiques, peuvent coloniser les habitats aquatiques permanents, chez Bufo calamita seule la gélatine compacte des oeufs sert à décourager les petits prédateurs

Testing postcombustion CO2 capture with CaO in a 1.7 MWt pilot facility

AbstractCalcium looping, CaL, is a new and rapidly developing technology that makes use of CaO as a high temperature regenerable sorbent of CO2. Previous theoretical and lab scale studies have shown that this technology could lead to a substantial reduction in the cost of CO2 capture and energy penalties because heat can be effectively recovered from this high temperature solid looping system. We report in this paper on the first results from a pilot plant designed to demonstrate the viability of postcombustion capture of CO2 using CaL under conditions comparable to those expected in a large scale plant. The pilot includes two interconnected circulating fluidized bed reactors of 15 m height: a CO2 absorber (carbonator) able to treat up to 2400kg/h (equivalent to about 1.7 MWth), and an oxy-fired CFB calciner with a firing power between 1-3 MWth. CO2 capture efficiencies over 90% have been experimentally observed, including continuous operation with highly cycled solids in the system (i.e. with modest CO2 carrying capacities). SO2 capture is shown to be extremely high, with concentrations of SO2 well below 10 ppmv at the exit of the carbonator. Closure of carbon and sulfur balances is satisfactory. These results should be valuable base for model validation and scaling up purposes in future stages of the EU FP7 “CaOling” project, under which this investigation has been carried out

Aportes para el desarrollo integral de las personas privadas de la libertad a partir del análisis exegético de Hebreos 10, 32 – 39 que promueva un evangelismo efectivo en la Cárcel Distrital de Varones y Anexo de Mujeres de Bogotá, D.C.

Con esta investigación se busca hacer un aporte para los líderes de las diferentes confesiones religiosas que realizan el acompañamiento a los privados de la libertad en la Cárcel Distrital de Varones y Anexo de Mujeres de la ciudad de Bogotá, D.C. (en adelante Cárcel Distrital), a la luz de la perícopa Hb 10, 32 – 39, que promueva su desarrollo integral a partir de un evangelismo efectivo sin importar la denominación religiosa a la que pertenezcan para reintegrarse en una sociedad que busca cada día ser más humana. Para hacer efectivo el propósito anteriormente descrito esta investigación indaga en aspectos como: El texto bíblico Hb 10, 32 – 39, el acompañamiento que puede realizar un líder consiste en, el seguimiento psico-espiritual y la Proyección post-condena (proyecto de vida) de las personas privadas de la libertad, reflejado en los propósitos de vida, tanto individual como propósito comunitario, esto con el fin que los grupos religiosos que trabajan en este ente carcelario, sin importar la denominación o confesión religiosa de cada uno de ellos, se involucren con las personas privadas de la libertad, y sea para ellos lo más importante pensar en la integralidad de la persona quien está a la expectativa de otra oportunidad de vida

Aportes para el desarrollo integral de las personas privadas de la libertad a partir del análisis exegético de Hebreos 10, 32 – 39 que promueva un evangelismo efectivo en la Cárcel Distrital de Varones y Anexo de Mujeres de Bogotá, D.C.

Con esta investigación se busca hacer un aporte para los líderes de las diferentes confesiones religiosas que realizan el acompañamiento a los privados de la libertad en la Cárcel Distrital de Varones y Anexo de Mujeres de la ciudad de Bogotá, D.C. (en adelante Cárcel Distrital), a la luz de la perícopa Hb 10, 32 – 39, que promueva su desarrollo integral a partir de un evangelismo efectivo sin importar la denominación religiosa a la que pertenezcan para reintegrarse en una sociedad que busca cada día ser más humana. Para hacer efectivo el propósito anteriormente descrito esta investigación indaga en aspectos como: El texto bíblico Hb 10, 32 – 39, el acompañamiento que puede realizar un líder consiste en, el seguimiento psico-espiritual y la Proyección post-condena (proyecto de vida) de las personas privadas de la libertad, reflejado en los propósitos de vida, tanto individual como propósito comunitario, esto con el fin que los grupos religiosos que trabajan en este ente carcelario, sin importar la denominación o confesión religiosa de cada uno de ellos, se involucren con las personas privadas de la libertad, y sea para ellos lo más importante pensar en la integralidad de la persona quien está a la expectativa de otra oportunidad de vida

Prevalence of chronic kidney disease in an urban Mexican population

Prevalence of chronic kidney disease in an urban Mexican population.BackgroundThe present study was primarily designed to assess the prevalence of chronic kidney disease in a Mexican urban population residing in Mexico and to evaluate certain biologic and socioeconomic conditions as risk factors for the development of renal disease.MethodsA population-based cross-sectional survey was conducted, which included 3564 patients of either gender aged >18 years, who were randomly selected from lists of patients assigned to primary care facilities in the city of Morelia. A questionnaire about personal current health status, kidney disease, diabetes, hypertension, or heart disease in close relatives, anthropometric and blood pressure measurements, and blood and urine samples to measure glucose, blood urea nitrogen, and creatinine was obtained for each patient. Creatinine clearance (Ccr) was calculated by the Cockcroft-Gault formula. Patients were classified in 1 of the 5 Ccr categories established by the Kidney Disease Outcomes Quality Initiative guidelines.ResultsThe prevalence rate of Ccr < 15mL/min was 1142 per million population, and that of Ccr <60mL/min 80,788 per million population. Alcohol and tobacco consumption, female gender, age >65 years, educational level < primary school, and income <US $4.00/day were significantly associated with reduced Ccr.ConclusionChronic kidney disease prevalence in this population is similar to that seen in industrialized countries. If these figures are similar to those of the entire Mexican population, only l out of 4 patients requiring renal replacement therapy in the country currently has access to it