Maskless selective growth of InGaAs/InP quantum wires on (100) GaAs

A new fabrication process to create InGaAs/InP quantum wires on (100) GaAs substrates is demonstrated. The process is based on the selectivity of the growth of InP on lines created by focused ion beam bombardment, together with the selectivity of the growth of InGaAs on the InP wires. Intense photoluminescene is observed from the wires and the emission shows clear polarization parallel and perpendicular to the wires. Cathodoluminescene images confirm that the luminescence originates from the wires.Peer reviewe

Transient four-wave mixing in T-shaped GaAs quantum wires

The binding energy of excitons and biexcitons and the exciton dephasing in T-shaped GaAs quantum wires is investigated by transient four-wave mixing. The T-shaped structure is fabricated by cleaved-edge overgrowth, and its geometry is engineered to optimize the one-dimensional confinement. In this wire of 6.6×24 nm2 size, we find a one-dimensional confinement of more than 20 meV, an inhomogeneous broadening of 3.4 meV, an exciton binding energy of 12 meV, and a biexciton binding energy of 2.0 meV. A dispersion of the homogeneous linewidth within the inhomogeneous broadening due to phonon-assisted relaxation is observed. The exciton acoustic-phonon-scattering coefficient of 6.1±0.5 μeV/K is larger than in comparable quantum-well structures

Evolutionary Computation, Optimization and Learning Algorithms for Data Science

A large number of engineering, science and computational problems have yet to be solved in a computationally efficient way. One of the emerging challenges is how evolving technologies grow towards autonomy and intelligent decision making. This leads to collection of large amounts of data from various sensing and measurement technologies, e.g., cameras, smart phones, health sensors, smart electricity meters, and environment sensors. Hence, it is imperative to develop efficient algorithms for generation, analysis, classification, and illustration of data. Meanwhile, data is structured purposefully through different representations, such as large-scale networks and graphs. We focus on data science as a crucial area, specifically focusing on a curse of dimensionality (CoD) which is due to the large amount of generated/sensed/collected data. This motivates researchers to think about optimization and to apply nature-inspired algorithms, such as evolutionary algorithms (EAs) to solve optimization problems. Although these algorithms look un-deterministic, they are robust enough to reach an optimal solution. Researchers do not adopt evolutionary algorithms unless they face a problem which is suffering from placement in local optimal solution, rather than global optimal solution. In this chapter, we first develop a clear and formal definition of the CoD problem, next we focus on feature extraction techniques and categories, then we provide a general overview of meta-heuristic algorithms, its terminology, and desirable properties of evolutionary algorithms

Glucose-induced posttranslational activation of protein phosphatases PP2A and PP1 in yeast

The protein phosphatases PP2A and PP1 are major regulators of a variety of cellular processes in yeast and other eukaryotes. Here, we reveal that both enzymes are direct targets of glucose sensing. Addition of glucose to glucose-deprived yeast cells triggered rapid posttranslational activation of both PP2A and PP1. Glucose activation of PP2A is controlled by regulatory subunits Rts1, Cdc55, Rrd1 and Rrd2. It is associated with rapid carboxymethylation of the catalytic subunits, which is necessary but not sufficient for activation. Glucose activation of PP1 was fully dependent on regulatory subunits Reg1 and Shp1. Absence of Gac1, Glc8, Reg2 or Red1 partially reduced activation while Pig1 and Pig2 inhibited activation. Full activation of PP2A and PP1 was also dependent on subunits classically considered to belong to the other phosphatase. PP2A activation was dependent on PP1 subunits Reg1 and Shp1 while PP1 activation was dependent on PP2A subunit Rts1. Rts1 interacted with both Pph21 and Glc7 under different conditions and these interactions were Reg1 dependent. Reg1-Glc7 interaction is responsible for PP1 involvement in the main glucose repression pathway and we show that deletion of Shp1 also causes strong derepression of the invertase gene SUC2. Deletion of the PP2A subunits Pph21 and Pph22, Rrd1 and Rrd2, specifically enhanced the derepression level of SUC2, indicating that PP2A counteracts SUC2 derepression. Interestingly, the effect of the regulatory subunit Rts1 was consistent with its role as a subunit of both PP2A and PP1, affecting derepression and repression of SUC2, respectively. We also show that abolished phosphatase activation, except by reg1Δ, does not completely block Snf1 dephosphorylation after addition of glucose. Finally, we show that glucose activation of the cAMP-PKA (protein kinase A) pathway is required for glucose activation of both PP2A and PP1. Our results provide novel insight into the complex regulatory role of these two major protein phosphatases in glucose regulation

ANTIHEMOSTATIC ACTIVITY of HEPARIN DISACCHARIDES and OLIGOSACCHARIDES OBTAINED BY CHEMICAL and ENZYMATIC FRAGMENTATION - REVERSAL of the HEMORRHAGIC ACTIVITY BY ATP and MYOSIN

ESCOLA PAULISTA MED,DEPT BIOQUIM,CP 20372,BR-04023 São Paulo,SP,BRAZILESCOLA PAULISTA MED,DEPT BIOQUIM,CP 20372,BR-04023 São Paulo,SP,BRAZILESCOLA PAULISTA MED,DEPT BIOQUIM,CP 20372,BR-04023 São Paulo,SP,BRAZILWeb of Scienc

Shaping an alternative smart city discourse through Twitter: Amsterdam and the role of creative migrants

Smart urbanism is driven by a discourse promoting technological solutions for urban problems often neglecting social needs. The aim of this paper is to identify signs of an alternative smart city discourse in the communication of creative skilled migrants active in The Netherlands. We employ a language analysis of the (geo-tagged) Twitter data in combination with a social network analysis. We show that creative migrants contribute to the smart city discourse by relating technology to common good. They broadcast globally information about innovative projects, social initiatives and environmental issues, setting the basis for the experimental city. We conclude that a social media analysis, based on the innovative methodology proposed, provides valuable knowledge that can inform urban planners on a more socially driven use of (digital) technology in the development of smart cities