Synergistic photoluminescent interaction of Si and CdTe quantum dots

Microsystem Technologies - We report the synergistic photoluminescent effect observed in heterogeneous colloidal solutions comprising different volumetric concentrations of Si and CdTe quantum dots...     

Efficiently solving linear bilevel programming problems using off-the-shelf optimization software

Many optimization models in engineering are formulated as bilevel problems. Bilevel optimization problems are mathematical programs where a subset of variables is constrained to be an optimal solution of another mathematical program. Due to the lack of optimization software that can directly handle and solve bilevel problems, most existing solution methods reformulate the bilevel problem as a mathematical program with complementarity conditions (MPCC) by replacing the lower-level problem with its necessary and sufficient optimality conditions. MPCCs are single-level non-convex optimization problems that do not satisfy the standard constraint qualifications and therefore, nonlinear solvers may fail to provide even local optimal solutions. In this paper we propose a method that first solves iteratively a set of regularized MPCCs using an off-the-shelf nonlinear solver to find a local optimal solution. Local optimal information is then used to reduce the computational burden of solving the Fortuny-Amat reformulation of the MPCC to global optimality using off-the-shelf mixed-integer solvers. This method is tested using a wide range of randomly generated examples. The results show that our method outperforms existing general-purpose methods in terms of computational burden and global optimality.     

Plasmon resonant amplification of a hot electron-driven photodiode

Nano Research - We report plasmon resonant excitation of hot electrons in a photodetector based on a metal/oxide/metal (Au/Al2O3/graphene) heterostructure. In this device, hot electrons, excited...     

Axial tolerance in the position of aberration compensators placed in a converging beam

To perform a null test of aspherical surfaces we used a computer-generated hologram or a lens or a mirror compensator to compensate the aspherical aberration. When compensating in a convergent light beam the axial position of this hologram or compensator is critical. A holographic compensator to be used in the convergent beam of light was designed and constructed. We have established some relations to determine the tolerance in the axial positioning of these compensators.     

Influence of external factors in resistance of Corynebacterium urealyticum to antimicrobial agents

Corynebacterium urealyticum is usually resistant to multiple antibiotics. We analyzed whether previous hospitalization and/or the use of antibiotics was a factor associated with the appearance of resistance to different antibiotics in C. urealyticum. Our findings suggest that resistant strains of C. urealyticum are likely to be acquired directly from the hospital environment and that the use of antibiotics in the hospital setting could favor the appearance of multiresistant strains.     

Metabolic role of glutamine and its importance in nutritional therapy

The advances in the field of nutritional support have made certain nutrients very relevant, which, although they have been known for a long time, at present represent an important chapter in nutrition, entering into what is known as "nutritional pharmacology". Among these nutrients is glutamine, an amino acid classified as non-essential, but which in certain circumstances may become to be considered as an "essential nutrient". In the present review, a review is made of its metabolic role, synthesis and degradation, metabolic routes and functions under normal conditions as well as under critical conditions. It is known that glutamine stimulates the synthesis and inhibits the degradation of proteins, it is an important vehicle for the transport of nitrogen and carbon within the tissues, it stimulates the synthesis of hepatic glycogen, it is an energy source for cell division, for the growth of different cells of rapid replication, such as enterocytes, colonocytes, and fibroblasts, as well as for other cells of the immune system, such as lymphocytes and macrophages. Thus its role in the maintenance of structure, in metabolism and function of the intestinal mucosa, and in dysfunctions of the immune system. In parenteral nutrition, at present there are no preparations which include it, given the stability problems which it presents, although attempts have been made to resolve this, using different possibilities, such as di-peptides. However, in enteral nutrition, the diets tend to include it, although in a small proportion. Nevertheless, having recognized its beneficial role in a certain type of patients, at present there are diets which contain glutamine in higher doses, with the object of attempting to cover the increased demands of glutamine which shall arise in these situations. The inclusion of glutamine in nutritional therapy is supported by multiple studies which reflect the beneficial effect of this nutrient, both in enteral nutrition as in parenteral nutrition.     

Interlocking, Ribbing and Folding: Explorations in Parametric Constructions

This paper presents three projects involving the design and fabrication of architectural structures through the use of different parametric software and digital manufacturing methods. The first project is a flexible partition composed of interlocking elements shaped using a laser-cutter. The second project is a university exhibition unit made with various wooden panels manufactured through a computer numerical controlled (CNC) system. The third project is a system of metal sheets folded by digital machines to create urban circulation spaces. The three works develop a parametric programming of geometry based on certain technical factors, enabling the recognition of patterns of interaction between formal and constructive issues involved in the definition of shapes through parametric controls. Differences in materials and processes are contrasted by similarities of function and conditions involved, creating a system of local, global, productive and environmental parameters that produces a repertoire of self-similar dimensions and variations as well as multiple possibilities of initial setups and final configurations. It suggests a specific field of design exploration focusing on the development of differentiated components and variable architectural configurations, in a kind of open parametric system.     

A hybrid solution to the multi-robot integrated exploration problem

In this paper we present a hybrid reactive/deliberative approach to the multi-robot integrated exploration problem. In contrast to other works, the design of the reactive and deliberative processes is exclusively oriented to the exploration having both the same importance level. The approach is based on the concepts of expected safe zone and gateway cell. The reactive exploration of the expected safe zone of the robot by means of basic behaviours avoids the presence of local minima. Simultaneously, a planner builds up a decision tree in order to decide between exploring the current expected safe zone or changing to other zone by means of travelling to a gateway cell. Furthermore, the model takes into account the degree of localization of the robots to return to previously explored areas when it is necessary to recover the certainty in the position of the robots. Several simulations demonstrate the validity of the approach.     

A quality evaluation methodology for health-related websites based on a 2-tuple fuzzy linguistic approach

Nowadays, the patients and physicians use the health-related websites as an important information source and, therefore, it is critical the quality evaluation of health- related websites. The quality assessment of health-related websites becomes especially relevant because their use imply the existence of a wide range of threats which can affect people’s health. Additionally, website quality evaluation can also contribute to maximize the exploitation of invested resources by organizations in the development of user-perceived quality websites. But there is not yet a clear and unambiguous definition of the concept of website quality and the debate about quality evaluation on the Web remains open. In this paper, we present a qualitative and user-oriented methodology for assessing quality of health-related websites based on a 2-tuple fuzzy linguistic approach. To identify the quality criteria set, a qualitative research has been carried out using the focus groups technique. The measurement method generates linguistic quality assessments considering the visitors’ judgements with respect to those quality criteria. The combination of the linguistic judgements is implemented without a loss of information by applying a 2-tuple linguistic weighted average operator. This methodology means an improvement on quality evaluation of health websites through the commitment to put users first.