Extraordinary absorption of decorated undoped graphene

We theoretically study absorption by an undoped graphene layer decorated with arrays of small particles. We discuss periodic and random arrays within a common formalism, which predicts a maximum absorption of $50\%$ for suspended graphene in both cases. The limits of weak and strong scatterers are investigated and an unusual dependence on particle-graphene separation is found and explained in terms of the effective number of contributing evanescent diffraction orders of the array. Our results can be important to boost absorption by single layer graphene due to its simple setup with potential applications to light harvesting and photodetection based on energy (F\"orster) rather than charge transfer.Comment: 5 pages, 3 figure

Innovation in the Public Library: where we are and where we go

La innovación, elemento fundamental en el momento histórico actual, resulta primoridal para que instituciones de todo tipo afronten con garantías los retos que se les plantean. Generalmente, estos procesos de innovación se basan fundamentalmente en el componente tecnológico, aunque también es posible llegar a innovar con otros recursos, planteamientos, y enfoques de servicio. La innovación también se está convirtiendo en una de las señas de identidad de las bibliotecas públicas españolas. Estas instituciones innovan principalmente a partir de la tecnología disponible ofreciendo servicios personalizados y adaptados en función de las necesidades e intereses de su comunidad de usuarios. Se analizan algunos casos paradigmáticos de servicios innovadores en bibliotecas públicas españolas.Innovation, a key element in the current historical moment, it primoridal for all institutions face up to the challenges guarantees they face. Generally, these innovation processes are based primarily on the technological component, although it is possible to innovate with other resources, approaches, and service approaches. Innovation also is becoming one of the hallmarks of Spanish public libraries. These institutions mainly innovate from available technology offering personalized and adapted according to the needs and interests of its user community. It analyzes some paradigmatic cases of innovative services in Spanish public librarie

Una generalización de los procesos estocásticos log-normal y de Gompertz como procesos de Itô

Estudiamos una ecuación diferencial estocástica de Itô que es una generalización de los modelos estocásticos logarítmico-normal y de Gomperz. Reducimos la ecuación mediante una transformación de cambio de estado a otra que resulta una generalización de la ecuación de Langevin, que rige el proceso de Uhlenbeck-Ornstein. A partir de la expresión analítica de las soluciones de ésta y de la original estudiamos las características estadísticas de ambos procesos solución, en particular los momentos de las distribuciones finito dimensionales, sus funciones de densidad de transición, las distribuciones límite y las condiciones de estacionariedad, obteniendo que la expresada generalización del proceso de U-O es el único proceso Gaussiano, Markoviano y estacionario no centrado en tiempo continuo. Por otra parte, se establece que las potencias del proceso lognormal-Gompertz generalizado satisfacen una E.D.E. del mismo tipo

Algunos recursos en internet para mejorar la enseñanza de la geografía

El gran aumento de información digitalizada, accesible on line, en un mundo globalizado, ha puesto a disposición del profesorado de Geografía y, en general, de Ciencias Sociales una gran cantidad de recursos que pueden ser utilizados en la enseñanza y también en la formación de los docentes. Algunos de estos recursos ya tenían cierta tradición de uso en formato convencional, apareciendo ahora más fácilmente accesibles; otros son nuevos recursos producidos digitalmente. Por ello tiene interés facilitar al profesorado una selección de estos recursos útiles para la enseñanza de la Geografía, organizados en diez grandes secciones temáticas, para un mejor aprovechamiento de los mismosThe great increase in on-line digital information in a global world has made available a great amount of resources that can be used by Geography and, in general, Social Sciences teachers in education and also in teacher training. Some of these resources already had a certain tradition of use in a conventional format but had now become more easily accessible; others are new digitally produced resources. That is why it is interesting to provide teachers a selection of these useful resources for Geography teaching, organized in ten great thematic sections in order to make a better use of them

The influence of crack-imbalance orientation and orbital evolution for an extended cracked Jeffcott rotor

Vibration peaks occurring at rational fractions of the fundamental rotating critical speed, here named Local Resonances, facilitate cracked shaft detection during machine shut-down. A modified Jeffcott-rotor on journal bearings accounting for gravity effects and oscillating around nontrivial equilibrium points is employed. Modal parameter selection allows this linear model to represent first mode characteristics of real machines. Orbit evolution and vibration patterns are analyzed, yielding useful results. Crack detection results indicate that, instead of 1x and 2x components, analysis of the remaining local resonances should have priority; this is due to crack-residual imbalance interaction and to 2x multiple induced origins. Therefore, local resonances and orbital evolution around 1/2, 1/3 and 1/4 of the critical speed are emphasized for various crack-imbalance orientations

A Recommendation Framework Based on the Analytic Network Process and its Application in the Semantic Technology Domain

When users face a certain problem needing a product, service, or action to solve it, selecting the best alternative among them can be a dicult task due to the uncertainty of their quality. This is especially the case in the domains where users do not have an expertise, like for example in Software Engineering. Multiple criteria decision making (MCDM) methods are methods that help making better decisions when facing the complex problem of selecting the best solution among a group of alternatives that can be compared according to different conflicting criteria. In MCDM problems, alternatives represent concrete products, services or actions that will help in achieving a goal, while criteria represent the characteristics of these alternatives that are important for making a decision

Associations between sedentary time, physical activity and bone health among older people using compositional data analysis

Introduction : Aging is associated with a progressive decrease in bone mass (BM), and being physical active is one of the main strategies to combat this continuous loss. Nonetheless, because daily time is limited, time spent on each movement behavior is co-dependent. The aim of this study was to determine the relationship between BM and movement behaviors in elderly people using compositional data analysis. Methods : We analyzed 871 older people [395 men (76.9 +/- 5.3y) and 476 women (76.7 +/- 4.7y)]. Time spent in sedentary behavior (SB), light physical activity (LPA) and moderate-to-vigorous physical activity (MVPA), was assessed using accelerometry. BM was determined by bone densitometry (DXA). The sample was divided according to sex and bone health indicators. Results : The combined effect of all movement behaviors (PA and SB) was significantly associated with whole body, leg and femoral region BM in the whole sample (p<0.05), with leg and pelvic BM (p<0.05) in men and, with whole body, arm and leg BM (p<0.05) in women. In men, arm and pelvic BM were negatively associated with SB and whole body, pelvic and leg BM were positively associated with MVPA (p<0.05). In women, whole body and leg BM were positively associated with SB. Arm and whole body BM were positively associated and leg BM was negatively associated with LPA and arm BM was negatively associated with MVPA (p<0.05). Women without bone fractures spent less time in SB and more in LPA and MVPA than the subgroup with bone fractures. Conclusion : We identified that the positive effect of MVPA relative to the other behaviors on bone mass is the strongest overall effect in men. Furthermore, women might decrease bone fracture risk through PA increase and SB reduction, despite the fact that no clear benefits of PA for bone mass were found