3,863 research outputs found

    The separate computation of arcs for optimal flight paths with state variable inequality constraints

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    Computation of arcs for optimal flight paths with state variable inequality constraint

    Optimal Control of Quantum Dynamics : A New Theoretical Approach

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    A New theoretical formalism for the optimal quantum control has been presented. The approach stems from the consideration of describing the time-dependent quantum system in terms of the real physical observables, viz., the probability density rho(x,t) and the quantum current j(x,t) which is well documented in the Bohm's hydrodynamical formulation of quantum mechanics. The approach has been applied for manipulating the vibrational motion of HBr in its ground electronic state under an external electric field.Comment: 4 figure

    Environmental and genetic influences on neurocognitive development: the importance of multiple methodologies and time-dependent intervention

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    Genetic mutations and environmental factors dynamically influence gene expression and developmental trajectories at the neural, cognitive, and behavioral levels. The examples in this article cover different periods of neurocognitive development—early childhood, adolescence, and adulthood—and focus on studies in which researchers have used a variety of methodologies to illustrate the early effects of socioeconomic status and stress on brain function, as well as how allelic differences explain why some individuals respond to intervention and others do not. These studies highlight how similar behaviors can be driven by different underlying neural processes and show how a neurocomputational model of early development can account for neurodevelopmental syndromes, such as autism spectrum disorders, with novel implications for intervention. Finally, these studies illustrate the importance of the timing of environmental and genetic factors on development, consistent with our view that phenotypes are emergent, not predetermined

    Energies of knot diagrams

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    We introduce and begin the study of new knot energies defined on knot diagrams. Physically, they model the internal energy of thin metallic solid tori squeezed between two parallel planes. Thus the knots considered can perform the second and third Reidemeister moves, but not the first one. The energy functionals considered are the sum of two terms, the uniformization term (which tends to make the curvature of the knot uniform) and the resistance term (which, in particular, forbids crossing changes). We define an infinite family of uniformization functionals, depending on an arbitrary smooth function ff and study the simplest nontrivial case f(x)=x2f(x)=x^2, obtaining neat normal forms (corresponding to minima of the functional) by making use of the Gauss representation of immersed curves, of the phase space of the pendulum, and of elliptic functions

    AGMIAL: implementing an annotation strategy for prokaryote genomes as a distributed system

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    We have implemented a genome annotation system for prokaryotes called AGMIAL. Our approach embodies a number of key principles. First, expert manual annotators are seen as a critical component of the overall system; user interfaces were cyclically refined to satisfy their needs. Second, the overall process should be orchestrated in terms of a global annotation strategy; this facilitates coordination between a team of annotators and automatic data analysis. Third, the annotation strategy should allow progressive and incremental annotation from a time when only a few draft contigs are available, to when a final finished assembly is produced. The overall architecture employed is modular and extensible, being based on the W3 standard Web services framework. Specialized modules interact with two independent core modules that are used to annotate, respectively, genomic and protein sequences. AGMIAL is currently being used by several INRA laboratories to analyze genomes of bacteria relevant to the food-processing industry, and is distributed under an open source license

    The historical vanishing of the Blazhko effect of RR Lyr from GEOS and Kepler surveys

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    RR Lyr is one of the most studied variable stars. Its light curve has been regularly monitored since the discovery of the periodic variability in 1899. Analysis of all observed maxima allows us to identify two primary pulsation states defined as pulsation over a long (P0 longer than 0.56684 d) and a short (P0 shorter than 0.56682 d) primary pulsation period. These states alternate with intervals of 13-16 yr, and are well defined after 1943. The 40.8 d periodical modulations of the amplitude and the period (i.e. Blazhko effect) were noticed in 1916. We provide homogeneous determinations of the Blazhko period in the different primary pulsation states. The Blazhko period does not follow the variations of P0 and suddenly diminished from 40.8 d to around 39.0 d in 1975. The monitoring of these periodicities deserved and deserves a continuous and intensive observational effort. For this purpose we have built dedicated, transportable and autonomous small instruments, Very Tiny Telescopes (VTTs), to observe the times of maximum brightness of RR Lyr. As immediate results the VTTs recorded the last change of P0 state in mid-2009 and extended the time coverage of the Kepler observations, thus recording a maximum O-C amplitude of the Blazhko effect at the end of 2008, followed by the historically smallest O-C amplitude in late 2013. This decrease is still ongoing and VTT instruments are ready to monitor the expected increase in the next few years.Comment: 10 pages, 6 figures. Accepted for publication in MNRAS. Contents of appendix B may be requested to first autho

    ‘Using my education to fight for my communities’: understanding how an equity-based STEM experience cultivated equity ethic and STEM identity development among women of colour in STEM

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    The pervasive myth that science, technology, engineering and mathematics (STEM) are purely objective subjects fosters significant disconnects between Black, Latinx, Asian, Brown and Indigenous students and K–12 STEM education, as the curriculum is often detached from their lived experiences. This disconnect leaves many students of colour feeling alienated in undergraduate and graduate STEM classrooms. Traditional STEM programmes rarely incorporate culturally responsive curricula that would allow students to connect more deeply with the content and develop their STEM identities. According to Carlone and Johnson’s framework of STEM identity development, students must view themselves as ‘doers’ of STEM. Without experiences that allow under-represented students to demonstrate competence and engage in disciplinary performance, their STEM identities are hindered. The I CAN PERSIST Initiative, a culturally responsive, evidence-based programme, aims to advance academic and career persistence among women and girls of colour in STEM. It seeks to reshape narratives about who can participate meaningfully in STEM through a curriculum designed to enhance students’ STEM identity development. This programme provides Black and Brown women and girls with opportunities to become ‘doers’ of STEM while integrating their lived experiences. Specifically, Black and Brown undergraduates and graduates facilitate lessons with local secondary school girls of colour interested in STEM, focusing on socio-scientific issues from a critical perspective. This article details the engagement of undergraduate and graduate women of colour in the I CAN PERSIST STEM Initiative through equity-based outreach activities that support their STEM identity development
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