Collective excitations in liquid D2 confined within the mesoscopic pores of a MCM-41 molecular sieve

We present a comparative study of the excitations in bulk and liquid D2 confined within the pores of MCM-41. The material (Mobile Crystalline Material-41) is a silicate obtained by means of a template that yields a partially crystalline structure composed by arrays of nonintersecting hexagonal channels of controlled width having walls made of amorphous SiO2. Its porosity was characterized by means of adsorption isotherms and found to be composed by a regular array of pores having a narrow distribution of sizes with a most probable value of 2.45 nm. The assessment of the precise location of the sample within the pores is carried out by means of pressure isotherms. The study was conducted at two pressures which correspond to pore fillings above the capillary condensation regime. Within the range of wave vectors where collective excitations can be followed up (0.3<Q<3.0 $\AA$&#8722;1), we found confinement brings forward a large shortening of the excitation lifetimes that shifts the characteristic frequencies to higher energies. In addition, the coherent quasielastic scattering shows signatures of reduced diffusivity.Comment: 6 page

A novel real space scattering theory: efficient characterization of colloidal crystals

XIV International Conference on Small-Angle Scattering (SAS09) 13–18 September 2009, Oxford, U

A novel real space scattering theory: efficient characterization of colloidal crystals

13 pags., 6 figs., 1 tab. -- XIV International Conference on Small-Angle Scattering (SAS09) 13–18 September 2009, Oxford, UKRecent advances in self-organized 3D ordered structures of submicron particles as colloidal crystals demand a precise quantitative characterization of the produced nano-structures. Small angle scattering is the technique of choice for such a task but a comprehensive quantitative modeling of the measurements is far from being straightforward. We have developed a theory based in the pair distances distribution which take into the account orientational, positional and staking disorder as well as finite size effects. We show also how the radial scattering length density of the constituent particles, essential for a comprehensive modeling of the experimental data, can be estimated from the position of the form factor local minima. The results reduce to sums of analytical functions over the distribution of pair distances and as such, are suitable for easy (automatic) parallelization.Work supported in part by grant MAT-2007-65711-C04-02 and MAT2007-65711-C04-01 from the Spanish Ministerio de Ciencia e Innovacion and by grant GR58/08-921556 under the Universidad Complutense de Madrid/ Banco de Santander financial scheme. We also thank the Microscopy Centre from the Universidad Complutense de Madrid for technical assistance

Raíces: plazas, tradición y cultura

Desde sus inicios como oficio se ha entendido el diseño gráfico como una disciplina orientada a la creación y transferencia de mensajes visuales construidos por medio de estrategias gráficas previamente estructuradas y planificadas para dar respuesta a necesidades comunicativas, apoyadas en una variedad de herramientas, técnicas y medios tanto impresos como digitales. Esta definición podría dar a entender que la función del diseño está más enfocada a dar respuesta a las necesidades estéticas de la comunicación sin un involucramiento directo con el tipo de mensaje que se transmite y las audiencias a las que va dirigido. Sin embargo el rol del diseño gráfico es mucho más complejo en la sociedad actual, es más relevante que los diseñadores trabajen con comunidades, haciendo parte de equipos de trabajo con comunicadores sociales, administradores, sociólogos, antropólogos, entre otras disciplinas académicas para intervenir tanto en la creación como en la aplicación de estrategias de comunicación..

Amazonia camtrap: A dataset of mammal, bird, and reptile species recorded with camera traps in the Amazon forest.

The Amazon forest has the highest biodiversity on earth. However, information on Amazonian vertebrate diversity is still deficient and scattered across the published, peer-reviewed and grey literature and in unpublished raw data. Camera traps are an effective non-invasive method of surveying vertebrates, applicable to different scales of time and space. In this study, we organized and standardized camera trap records from different Amazon regions to compile the most extensive dataset of inventories of mammal, bird and reptile species ever assembled for the area. The complete dataset comprises 154,123 records of 317 species (185 birds, 119 mammals and 13 reptiles) gathered from surveys from the Amazonian portion of eight countries (Brazil, Bolivia, Colombia, Ecuador, French Guiana, Peru, Suriname and Venezuela). The most frequently recorded species per taxa were: mammals - Cuniculus paca (11,907 records); birds - Pauxi tuberosa (3,713 records); and reptiles - Tupinambis teguixin (716 records). The information detailed in this data paper opens-up opportunities for new ecological studies at different spatial and temporal scales, allowing for a more accurate evaluation of the effects of habitat loss, fragmentation, climate change and other human-mediated defaunation processes in one of the most important and threatened tropical environments in the world. The dataset is not copyright restricted; please cite this data-paper when using its data in publications and we also request that researchers and educators inform us of how they are using this data. [Abstract copyright: This article is protected by copyright. All rights reserved.