Chaotic Strings in AdS/CFT.

Holographic theories with classical gravity duals are maximally chaotic; i.e., they saturate the universal bound on the rate of growth of chaos [J. Maldacena, S. H. Shenker, and D. Stanford, J. High Energy Phys. 08 (2016) 106JHEPFG1029-847910.1007/JHEP08(2016)106]. It is interesting to ask whether this property is true only for leading large N correlators or if it can show up elsewhere. In this Letter, we consider the simplest setup to tackle this question: a Brownian particle coupled to a thermal ensemble. We find that the four-point out-of-time-order correlator that diagnoses chaos initially grows at an exponential rate that saturates the chaos bound, i.e., with a Lyapunov exponent λ_{L}=2π/β. However, the scrambling time is parametrically smaller than for plasma excitations, t_{*}∼βlogsqrt[λ] instead of t_{*}∼βlogN^{2}. Our result shows that, at least in certain cases, maximal chaos can be attained in the probe sector without the explicit need of gravitational degrees of freedom.Funded by SCOAP3

On the Binding of Congo Red to Amyloid Fibrils

Amyloids are characterized by their capacity to bind Congo red (CR), one of the most used amyloid‐specific dyes. The structural features of CR binding were unknown for years, mainly because of the lack of amyloid structures solved at high resolution. In the last few years, solid‐state NMR spectroscopy enabled the determination of the structural features of amyloids, such as the HET‐s prion forming domain (HET‐s PFD), which also has recently been used to determine the amyloid-CR interface at atomic resolution. Herein, we combine spectroscopic data with molecular docking, molecular dynamics, and excitonic quantum/molecular mechanics calculations to examine and rationalize CR binding to amyloids. In contrast to a previous assumption on the binding mode, our results suggest that CR binding to the HET‐s PFD involves a cooperative process entailing the formation of a complex with 1:1 stoichiometry. This provides a molecular basis to explain the bathochromic shift in the maximal absorbance wavelength when CR is bound to amyloids

El diagnóstico del cáncer oral en el paciente geriátrico

El cáncer oral es una patología frecuente y creciente en el mundo occidental, su incidencia se incrementa año tras año, a pesar de que su localización, en una cavidad fácilmente accesible y explorable permitiría un diagnóstico temprano del mismo, o de las alteraciones potencialmente malignas. Las cifras de nuestro país sitúan una incidencia de 6,7 casos nuevos al año por 100.000 habitantes, con una proporción hombre/mujer de 3 a 1. La proporción de estas neoplasias aumenta de forma gradual con la edad, la posibilidad de que una lesión ulcerosa o proliferativa de cavidad oral, sea un carcinoma es mucho más elevada en pacientes mayores de 65 años. Es nuestra obligación el concienciar a nuestros pacientes, en el cese de hábitos nocivos y en la educación para establecer de la autoexploración una actividad habitual. Sin duda, una exhaustiva exploración física es la primera medida diagnóstica que poseemos asociada ante la mínima sospecha a la realización de una biopsia y el correspondiente estudio histopatológico, que puede establecer la potencialidad maligna de la lesión, así como la evolución de la misma. Disponemos, en la actualidad, de métodos complementarios de diagnósticos, que desde los tradicionales colorantes vitales, pasando por métodos ópticos, hasta la utilización de novedosas técnicas de identificación de receptores moleculares, de alteraciones cromosómicas podrían ser de utilidad en la orientación de factores de riesgo en pacientes predispuestos a padecer la patología, todo ello con el futuro puesto en identificar todos estos riesgos potenciales con un simple análisis de saliva. Lo cierto es que a día de hoy el mejor diagnóstico es la prevención y en el peor de los casos realizarlo lo más precozmente posible para mejorar las perspectivas vitales y la calidad de vida de nuestros pacientes

Linfangioma lingual: caso clínico

Los linfangiomas son masas de mayor o menor extensión, de origen controvertido. Son malformaciones congénitas del sistema linfático, poco frecuentes, que distintos autores consideran de carácter neoplásico, hamartomatoso o de displasia congénita. Afectan piel o mucosas, así como tejidos subcutáneos o submucosos, en cualquier localización. Se clasifican en superficiales (circunscritos) y profundos (cavernosos, higromas, quísticos), en base a su asiento y al tamaño de las formaciones vasculares linfáticas

Photodegradation of Phenol over a Hybrid Organo-Inorganic Material: Iron(II) Hydroxyphosphonoacetate

Water treatment is a hot topic, and it will become much more important in the decades ahead. Advanced oxidation processes are being increasingly used for organic contaminant removal, for example using photo-Fenton reactions. Here we report the use of an organo-inorganic hybrid, Fe[HO3PCH(OH)COO]·2H2O, as Fenton photocatalyst for phenol oxidation with H2O2 under UVA radiation. Preactivation, catalyst content, and particle size parameters have been studied/optimized for increasing phenol mineralization. Upon reaction, iron species are leached from the catalyst making a homogeneous catalysis contribution to the overall phenol photo-oxidation. Under optimized conditions, the mineralization degree was slightly larger than 90% after 80 min of irradiation. Analysis by X-ray photoelectron spectroscopy revealed important chemical modifications occurring on the surface of the catalyst after activation and phenol photodegradation. The sustained slow delivery of iron species upon phenol photoreaction is advantageous as the mixed heterogeneous−homogeneous catalytic processes result in very high phenol mineralization.Proyecto nacional MAT2010-1517

Ubiquitous healthy diatoms in the deep sea confirm deep carbon injection by the biological pump

The role of the ocean as a sink for CO2 is partially dependent on the downward transport of phytoplankton cells packaged within fast-sinking particles. However, whether such fast-sinking mechanisms deliver fresh organic carbon down to the deep bathypelagic sea and whether this mechanism is prevalent across the ocean requires confirmation. Here we report the ubiquitous presence of healthy photosynthetic cells, dominated by diatoms, down to 4,000 m in the deep dark ocean. Decay experiments with surface phytoplankton suggested that the large proportion (18%) of healthy photosynthetic cells observed, on average, in the dark ocean, requires transport times from a few days to a few weeks, corresponding to sinking rates (124–732 m d−1) comparable to those of fast-sinking aggregates and faecal pellets. These results confirm the expectation that fast-sinking mechanisms inject fresh organic carbon into the deep sea and that this is a prevalent process operating across the global oligotrophic ocean

Interactive Effect of UVR and Phosphorus on the Coastal Phytoplankton Community of the Western Mediterranean Sea: Unravelling Eco- Physiological Mechanisms

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