Exploiting timescale separation in micro and nano flows

This paper was presented at the 3rd Micro and Nano Flows Conference (MNF2011), which was held at the Makedonia Palace Hotel, Thessaloniki in Greece. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, Aristotle University of Thessaloniki, University of Thessaly, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute.In this paper we describe how timescale separation in micro/nano flows can be exploited for computational acceleration. A modified version of the seamless heterogenous multiscale method (SHMM) is proposed: a multi-step SHMM. This maintains the main advantages of SHMM (e.g., re-initialisation of micro data is not required; temporal gearing (computational speed-up) is easily controlled; and it is applicable to full and intermediate degrees of timescale separation) while improving on accuracy and greatly reducing the number of macroscopic computations and micro/macro coupling instances required. The improved accuracy of the multi-step SHMM is demonstrated for two canonical one-dimensional transient flows (oscillatory Poiseuille and oscillatory Couette flow) and for rarefied-gas oscillatory Poiseuille flow.This research is financially supported by the EPSRC Programme Grant EP/I011927/1

Effects of crossed electric and magnetic fields on the electronic and excitonic states in bulk GaAs and GaAs/Ga1-xAlxAs quantum wells

The variational procedure in the effective-mass and parabolic-band approximations is used in order to investigate the effects of crossed electric and in-plane magnetic fields on the electronic and exciton properties in semiconductor heterostructures. Calculations are performed for bulk GaAs and GaAs/Ga1-xAlxAs quantum wells, for applied magnetic fields parallel to the layers and electric fields in the growth direction, and it is shown that the combined effects on the heterostructure properties of the applied crossed electric and magnetic fields and the direct coupling between the center-of-mass and internal exciton motions may be dealt with via a simple parameter representing the spatial distance between the centers of the electron and hole magnetic parabolas. Exciton properties are analyzed by using a simple hydrogenlike envelope excitonic wave function and present theoretical results are found in fair agreement with available experimental measurements on the diamagnetic shift of the photoluminescence peak position of GaAs/Ga1-xAlxAs quantum wells under in-plane magnetic fields.75

Carta que el R.P.M. Fray Bautista Abad, Vicario provincial del Reyno de Valencia, del Orden de San Agustin escriuio al ... Duque de Veraguas ... : [Texto impreso] [setiembre à 18 de 1680]

Según Medina, Biblioteca Hispanoamericana, VI, 6152, podría estar impresa en Madrid, 1680Tit. tomado de comienzo de textoSegún Medina, Biblioteca Hispanoamericana, VI, 6152, podría estar impresa en Madrid, 1680Texto fechado en: "Setiembre à 18 de 1680"Sign.: A

Collaborative and Inclusive Process with the Autism Community: A Case Study in Colombia About Social Robot Design

One of the most promising areas in which social assistive robotics has been introduced is therapeutic intervention for children with autism spectrum disorders (CwASD). Even though there are promising results in therapeutic contexts, there is a lack of guidelines on how to select the appropriate robot and how to design and implement the child-robot interaction. The use of participatory design (PD) methods in the design of technology-based processes for CwASD is a recognition of the stakeholders as "experts" in their fields. This work explores the benefits brought by the use of PD methods in the design of a social robot, with a specific focus on their use in autism spectrum disorders therapies on the Colombian autism community. Based on what proved to be effective in our previous research, we implemented participatory methods for both the CwASD and the stakeholders. The process leverages the active role of participants using a focus group approach with parents and specialists, and scene cards, narrative and handmade generative methods with the children. To overcome some challenges of traditional PD processes, where not all community actors are considered, we included a Colombian community consisting of therapists, nurses, caregivers and parents. The proposed PD process provides an opportunity to learn from several community actors (and thus different cultural and social aspects of developing countries), improving traditional robot design methods. In this way, the findings are summarized through a set of guidelines regarding the design of a social robot-device suitable to be implemented for robot-assisted therapy for CwASD

Exciton properties in zincblende InGaN-GaN quantum wells under the effects of intense laser fields

ABSTRACT: In this work, we study the exciton states in a zincblende InGaN/GaN quantum well using a variational technique. The system is considered under the action of intense laser fields with the incorporation of a direct current electric field as an additional external probe. The effects of these external influences as well as of the changes in the geometry of the heterostructure on the exciton binding energy are discussed in detail

Rarity of monodominance in hyperdiverse Amazonian forests.

Tropical forests are known for their high diversity. Yet, forest patches do occur in the tropics where a single tree species is dominant. Such "monodominant" forests are known from all of the main tropical regions. For Amazonia, we sampled the occurrence of monodominance in a massive, basin-wide database of forest-inventory plots from the Amazon Tree Diversity Network (ATDN). Utilizing a simple defining metric of at least half of the trees ≥ 10 cm diameter belonging to one species, we found only a few occurrences of monodominance in Amazonia, and the phenomenon was not significantly linked to previously hypothesized life history traits such wood density, seed mass, ectomycorrhizal associations, or Rhizobium nodulation. In our analysis, coppicing (the formation of sprouts at the base of the tree or on roots) was the only trait significantly linked to monodominance. While at specific locales coppicing or ectomycorrhizal associations may confer a considerable advantage to a tree species and lead to its monodominance, very few species have these traits. Mining of the ATDN dataset suggests that monodominance is quite rare in Amazonia, and may be linked primarily to edaphic factors

Magnetic field dependence and bottlenecklike behavior of the ESR spectra in YbRh2Si2

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Electron spin resonance (ESR) experiments at different fields or frequencies (4.1 <=nu <= 34.4 GHz) in the Kondo lattice (T-K similar or equal to 25 K) YbRh2Si2 single-crystal compounds confirmed the observation of a single anisotropic Dysonian resonance with g(perpendicular to c)congruent to 3.55 and no hyperfine components for 4.2 less than or similar to T less than or similar to 20 K. However, our studies differently reveal that (i) the ESR spectra for H-perpendicular to c show strong-field-dependent spin-lattice relaxation, (ii) a weak-field and temperature-dependent effective g value, (iii) a dramatic suppression of the ESR intensity beyond 15% of Lu doping, and (iv) a strong sample and Lu-doping (<= 15%) dependence of the ESR data. These results suggest a different scenario where the ESR signal may be associated to a coupled Yb3+-conduction electron resonant collective mode with a strong bottleneck and dynamiclike behavior.793Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)NSF (USA)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq