Chaotic exploration and learning of locomotion behaviours

We present a general and fully dynamic neural system, which exploits intrinsic chaotic dynamics, for the real-time goal-directed exploration and learning of the possible locomotion patterns of an articulated robot of an arbitrary morphology in an unknown environment. The controller is modeled as a network of neural oscillators that are initially coupled only through physical embodiment, and goal-directed exploration of coordinated motor patterns is achieved by chaotic search using adaptive bifurcation. The phase space of the indirectly coupled neural-body-environment system contains multiple transient or permanent self-organized dynamics, each of which is a candidate for a locomotion behavior. The adaptive bifurcation enables the system orbit to wander through various phase-coordinated states, using its intrinsic chaotic dynamics as a driving force, and stabilizes on to one of the states matching the given goal criteria. In order to improve the sustainability of useful transient patterns, sensory homeostasis has been introduced, which results in an increased diversity of motor outputs, thus achieving multiscale exploration. A rhythmic pattern discovered by this process is memorized and sustained by changing the wiring between initially disconnected oscillators using an adaptive synchronization method. Our results show that the novel neurorobotic system is able to create and learn multiple locomotion behaviors for a wide range of body configurations and physical environments and can readapt in realtime after sustaining damage

Teachers\u27 and Students\u27 Views of Reading Fluency: Issues of Consequential Validity in Adopting One-minute Reading Fluency Assessments

In this study, we investigate assertions that use of one-minute oral reading fluency measures, such as the Dynamic Indicators of Basic Early Literacy Skills (DIBELS) Oral Reading Fluency (ORF) assessment and the aimsweb Reading CBM (R-CBM), may generate negative educational consequences, specifically teaching to ORF tests, increased pressure and anxiety for teachers and students, and misuse of ORF measures and results. We present results of a survey designed to gain perspective on teachers’ and students’ views related to these potential negative consequences. Data gained from 77 teachers and 875 students in two districts generally do not support assertions of teaching to the test, but do support some caution with respect to use of ORF measurements and data, and issues of anxiety, particularly from more vulnerable students. This paper provides detailed results across teachers and students, and implications for practice. Since the publication of the National Reading Panel report (2000), increased attention has been paid to assessing oral reading fluency (ORF). Many districts use one-minute ORF measures, such as the Dynamic Indicators of Basic Early Literacy Skills (DIBELS) Oral Reading Fluency assessment (Good & Kaminski, 2002) and aimsweb Reading CBM (R-CBM) (NCS Pearson, 2014). However, one-minute ORF measures have garnered intense scrutiny, with critics warning unintended negative effects of their use, such as teaching to the test (Tierney & Thome, 2006), increased pressure and anxiety for teachers and students (Goodman, 2006), and misuse of measures and results (Valencia, Smith, Reece, Li, Wixon, & Newman, 2010). In our search of the literature (Education Full Text, PsycINFO, PsycARTICLES, Science Direct, ProQuest), we found few empirical studies investigating or confirming negative consequences of using one-minute measures. Our study begins to address this void by surveying teachers and students in two districts that mandate one-minute ORF measures to understand their perceptions of the measures, how measures are used in schools, and how teachers engage students in instructional practices related to ORF

Theory of spin, electronic and transport properties of the lateral triple quantum dot molecule in a magnetic field

We present a theory of spin, electronic and transport properties of a few-electron lateral triangular triple quantum dot molecule in a magnetic field. Our theory is based on a generalization of a Hubbard model and the Linear Combination of Harmonic Orbitals combined with Configuration Interaction method (LCHO-CI) for arbitrary magnetic fields. The few-particle spectra obtained as a function of the magnetic field exhibit Aharonov-Bohm oscillations. As a result, by changing the magnetic field it is possible to engineer the degeneracies of single-particle levels, and thus control the total spin of the many-electron system. For the triple dot with two and four electrons we find oscillations of total spin due to the singlet-triplet transitions occurring periodically in the magnetic field. In the three-electron system we find a transition from a magnetically frustrated to the spin-polarized state. We discuss the impact of these phase transitions on the addition spectrum and the spin blockade of the lateral triple quantum dot molecule.Comment: 30 pages (one column), 9 figure

X-ray absorption branching ratio in actinides: LDA+DMFT approach

To investigate the x-ray absorption (XAS) branching ratio from the core 4d to valence 5f states, we set up a theoretical framework by using a combination of density functional theory in the local density approximation and Dynamical Mean Field Theory (LDA+DMFT), and apply it to several actinides. The results of the LDA+DMFT reduces to the band limit for itinerant systems and to the atomic limit for localized f electrons, meaning a spectrum of 5f itinerancy can be investigated. Our results provides a consistent and unified view of the XAS branching ratio for all elemental actinides, and is in good overall agreement with experiments.Comment: 6 pages, 4 figure