High-performance solution of hierarchical equations of motions for studying energy-transfer in light-harvesting complexes

Excitonic models of light-harvesting complexes, where the vibrational degrees of freedom are treated as a bath, are commonly used to describe the motion of the electronic excitation through a molecule. Recent experiments point toward the possibility of memory effects in this process and require to consider time non-local propagation techniques. The hierarchical equations of motion (HEOM) were proposed by Ishizaki and Fleming to describe the site-dependent reorganization dynamics of protein environments (J. Chem. Phys., 130, p. 234111, 2009), which plays a significant role in photosynthetic electronic energy transfer. HEOM are often used as a reference for other approximate methods, but have been implemented only for small systems due to their adverse computational scaling with the system size. Here, we show that HEOM are also solvable for larger systems, since the underlying algorithm is ideally suited for the usage of graphics processing units (GPU). The tremendous reduction in computational time due to the GPU allows us to perform a systematic study of the energy-transfer efficiency in the Fenna-Matthews-Olson (FMO) light-harvesting complex at physiological temperature under full consideration of memory-effects. We find that approximative methods differ qualitatively and quantitatively from the HEOM results and discuss the importance of finite temperature to achieve high energy-transfer efficiencies.Comment: 14 pages; Journal of Chemical Theory and Computation (2011

Respuesta de la vegetación a un fuego controlado en la Provincia Fitogeográfica del Monte, Argentina

El fuego es un proceso ecológico clave en la mayoría de los ecosistemas terrestres. Por lo tanto, la comprensión de la respuesta de la vegetación al fuego es esencial para su manejo. El objetivo de este trabajo fue estudiar el efecto de un fuego controlado, realizado a fines del verano, sobre la cobertura y densidad de las principales especies leñosas y herbáceas en la Provincia Fitogeográfica del Monte, Argentina. En general, después del fuego controlado el porcentaje de cobertura media de las especies leñosas fue significativamente menor (p0,05) en la densidad media de las especies leñosas a lo largo del período de estudio. La cobertura foliar media de las gramíneas perennes deseables, excepto en dos fechas de muestreo, fue significativamente mayor (p0,05) entre tratamientos en la densidad de las gramíneas perennes deseables. La densidad de las gramíneas perennes intermedias fue consistentemente menor en el tratamiento quemado que en el tratamiento control, pero sólo ocasionalmente las diferencias fueron significativas (p0.05) were detected in woody species mean density among treatments throughout the whole study. Desirable perennial grass mean percentage foliar cover, except at two sampling dates, was higher (p<0.05) in the controlled fire treatment than in the control. Contrarily, mean percentage foliar cover of intermediate perennial grasses was lower in the fire treatment than in the control, although differences were not always significant (p<0.05). No significant differences (p<0.05) in desirable perennial grass density were detected among treatments. Intermediate perennial grass density was consistently lower in the fire than in the control treatment, although differences were not always significant at p<0.05. Desirable annual grass and forb foliar covers were slightly higher in the fire than in the control treatment. Our results suggest that the reduction of woody species cover might have favored the foliar cover increase of the desirable perennial grasses. Moreover, our results suggest that a single, controlle burn would not seem to start a plant species replacement sequence, and that the plant community would persist with no variation in the density of the major woody species and the most prominent perennial grasses.Fil: Pelaez, Daniel Valerio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Giorgetti, Hugo Dosindo. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; ArgentinaFil: Montenegro, Oscar Alberto. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; ArgentinaFil: Elia, Omar Raul. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Rodriguez, Gustavo Dionisio. Provincia de Buenos Aires. Ministerio de Asuntos Agrarios. Chacra Experimental de Patagones; ArgentinaFil: Boo, Roberto Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Mayor, Mirta Doris. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Busso, Carlos Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida. Universidad Nacional del Sur. Centro de Recursos Naturales Renovables de la Zona Semiárida; Argentina. Universidad Nacional del Sur. Departamento de Agronomía; Argentin

Tres, dos, uno...¡tiempo de Cervantes!

ES: Con este taller pretendemos acercar al alumnado la figura del escritor Miguel de Cervantes, através de una serie televisiva de actualidad, El Ministerio del Tiempo. Como algunosreferentes literarios y culturales pueden resultarles ajenos o lejanos a los estudiantes,consideramos que podemos propiciar su aproximación recurriendo a estrategias motivadoras y areferentes más cercanos.Así, tomando como eje el capítulo «Tiempo de hidalgos», que gira en torno a la figura del escritor, yque pertenece a la 2.ª temporada de la serie, hemos creado un conjunto de actividades de previsionado,simultaneidad al visionado y postvisionado, cuyo objetivo principal es dar a conocer a nuestrosestudiantes la personalidad literaria y humana del autor de El Quijote mediante un viaje al pasadoemocionante y culturalmente enriquecedor. Además, con la tarea final que planteamos facilitamosasimismo el acercamiento de los estudiantes a episodios relevantes de la historia de su propio paísThe purpose of this practical experience is to bring the figure of Miguel de Cervantes to our students,from a current hit TV series, El Ministerio del Tiempo. As we have consciousness that some referencescan be uninspiring to our students, mainly if they are culturally far from them, we aim to promote thisapproach by using motivational strategies. Thus, starting from the second season «Tiempo dehidalgos» episode, based on the famous writer, whos literary and human personality we want to makeknown by offering students an unforgettable journey into the past, we have designed several tasks tobe performed by students before, during and after the episode watching. Besides, the object of the finaltask we have designed is to approach students to the history of their own countries

Iron bioaccessibility and sensory analysis of extruded cereals fortified with different Fe sources

To increase iron (Fe) intake in Fe deficiency-risk groups the combination of Fe source and food-vehicle must be chosen in order to minimize inhibitory effects of food matrix. Fe dialyzability and sensory properties were tested in six model systems (MS) made with extruded cereals fortified with different Fe sources such as FeNaEDTA, FeSO4 and EDTA/FeSO4 among others and with or without the addition of milk. Proximate composition and phytate content were also evaluated. Results showed that Fe dialyzability from samples fortified with FeNaEDTA was less affected by the presence of inhibitory factors such as phytates and milk. The addition of FeSO4 to the extrudates showed sensory differences. Furthermore, fortification with EDTA/FeSO4 or FeNaEDTA showed no sensory differences compared with unfortified or Feº (elemental iron) fortified matrix, with the advantage of increased iron bioaccessibility.Fil: Cagnasso, Carolina Elisa. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Calviño, Amalia Mirta. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lopez, Laura Beatriz. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cellerino, Karina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Dyner, Luis Marcelo. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Binaghi, Maria Julieta. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Rodriguez, Viviana. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; ArgentinaFil: Drago, Silvina Rosa. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología de los Alimentos; ArgentinaFil: Gonzalez, Rolando Jose. Universidad Nacional del Litoral. Facultad de Ingeniería Química. Instituto de Tecnología de los Alimentos; ArgentinaFil: Valencia, Mirta Eva. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica; Argentin

Epidemiological modelling of the 2005 French riots: a spreading wave and the role of contagion

As a large-scale instance of dramatic collective behaviour, the 2005 French riots started in a poor suburb of Paris, then spread in all of France, lasting about three weeks. Remarkably, although there were no displacements of rioters, the riot activity did travel. Access to daily national police data has allowed us to explore the dynamics of riot propagation. Here we show that an epidemic-like model, with just a few parameters and a single sociological variable characterizing neighbourhood deprivation, accounts quantitatively for the full spatio-temporal dynamics of the riots. This is the first time that such data-driven modelling involving contagion both within and between cities (through geographic proximity or media) at the scale of a country, and on a daily basis, is performed. Moreover, we give a precise mathematical characterization to the expression “wave of riots”, and provide a visualization of the propagation around Paris, exhibiting the wave in a way not described before. The remarkable agreement between model and data demonstrates that geographic proximity played a major role in the propagation, even though information was readily available everywhere through media. Finally, we argue that our approach gives a general framework for the modelling of the dynamics of spontaneous collective uprisings

The collisional evolution of undifferentiated asteroids and the formation of chondritic meteoroids

Most meteorites are fragments from recent collisions experienced in the asteroid belt. In such a hypervelocity collision, the smaller collision partner is destroyed, whereas a crater on the asteroid is formed or it is entirely disrupted, too. The present size distribution of the asteroid belt suggests that an asteroid with a 100 km radius is encountered 1014 times during the lifetime of the solar system by objects larger than 10 cm in radius; the formed craters cover the surface of the asteroid about 100 times. We present a Monte Carlo code that takes into account the statistical bombardment of individual infinitesimally small surface elements, the subsequent compaction of the underlying material, and the formation of a crater and a regolith layer. For the entire asteroid, 10,000 individual surface elements are calculated. We compare the ejected material from the calculated craters with the shock stage of meteorites with low petrologic type and find that these most likely stem from smaller parent bodies that do not possess a significant regolith layer. For larger objects, which accrete a regolith layer, a prediction of the thickness depending on the largest visible crater can be made. Additionally, we compare the crater distribution of an object initially 100 km in radius with the shape model of the asteroid (21) Lutetia, assuming it to be initially formed spherical with a radius that is equal to its longest present ellipsoid length. Here we find the shapes of both objects to show resemblance to each other.Facultad de Ciencias Astronómicas y GeofísicasInstituto Argentino de Radioastronomí

Test de figura humana en pacientes en edad pediátrica con antecedentes de abuso sexual. Estudio de casos

Se planteó evaluar presencia de indicadores de abuso sexual en la infancia (ASI) con indicadores de Boscato en los test de figura humana de niñas con y sin antecedentes de ASI en la Cátedra de Psiquiatría del Hospital de Clínicas. Estudio exploratorio, de corte transversal. Se realizó un análisis de test gráficos de figura humana en 16 pacientes: 8 con antecedentes de ASI y 8 sin ASI. Intensidad de la agresión: Descarga motora: en 6 del total de 8 pacientes con ASI, contra sin hallazgo en pacientes sin ASI. Concepción de sí mismo: percepción de estar traumatizado, en 2 de los 8 pacientes con ASI y en ninguna sin ASI. Micrografía: no presente en las pacientes con ASI en cambio sí en 1 de las pacientes sin ASI. Negación: en 2 del total de pacientes con ASI y en ningún paciente sin ASI. Vulnerabilidad (necesidad de defensa): en 6 del total de pacientes con ASI y en ningún paciente sin ASI. Percepciones sensoriales: un signo presente en 1 paciente sin ASI y ausente en pacientes con ASI. Registro somático, Heridas o marcas en el cuerpo: en 6 (75%) del total de pacientes con ASI y en 2 de pacientes sin ASI. Se hallaron indicadores específicos para detección del abuso sexual Infantil que se corresponden con Intensidad de la agresión, concepción de sí mismo y en menor grado: registro somático y relación social

Long-Term Follow-Up of Children Treated With Peginterferon and Ribavirin for Hepatitis C Virus Infection

Objectives: The aim of the study was to describe the 5-year follow-up of children who received peginterferon and ribavirin in a global, open-label study. Methods: A 5-year follow-up study of 107 children and adolescents ages 3 to 17 years with chronic hepatitis C virus infection who received peginterferon and ribavirin for 24 or 48 weeks. No drugs were administered during follow-up. Results: Ninety-four patients were enrolled in the long-term follow-up portion of the study;the median duration of follow-up was 287 weeks (range, 73-339). Of 63 patients with sustained virologic response who were enrolled, 54 completed 5 years of follow-up;none had relapse in the 5-year follow-up period. Significant decreases in height z scores were observed during treatment. The effect of treatment on height z score was larger in patients treated for 48 weeks compared with those treated for 24 weeks (mean change from baseline to the end of treatment was -0.13 [P < 0.001] and -0.44 [P < 0.001] in the 247 and 48-week treatment groups, respectively). Among patients treated for 24 weeks, full recovery of height z scores to baseline was observed by 1 year of follow-up, whereas only partial recovery was observed during 5 years of follow-up in patients treated for 48 weeks (mean change from baseline to the final follow-up visit was -0.16 (P=NS) and 0.32 (P < 0.05) in the 24- and 48-week treatment groups, respectively). Similar patterns were observed for weight and body mass index z scores. Conclusions: Impairment of growth should be considered when assessing the risk-benefit profile of peginterferon/ribavirin therapy in children with hepatitis C virus infection. In deciding to treat children with chronic hepatitis C virus, considerations should include both deferring treatment in patients during optimal growth periods, and the possibility that interferon free regimens may be available to children in the next 5 to 10 years