436 research outputs found
Interventions and classroom contexts that promote Self-Regulated learning: Two intervention studies in United Kingdom primary classrooms
This paper has 2 aims: (a) identify pedagogical practices and classroom arrangements that foster self-regulated learning (SRL) on the basis of extant research and (b) illustrate, through the description of 2 intervention studies conducted in the United Kingdom, how those SRL promoting features can be used to design educational interventions appropriate for young students. Through a purposive sample of primary schools, both studies investigated the effects of collaborative problem solving, play, and dialogue on children’s SRL and academic achievement, following quasi-experimental pre- and post-test designs, comprising concurrent (Study 1) and retrospective (Study 2) comparison groups. Assessment and intervention data was video recorded and coded. In Study 1 the intervention group (57 1st grade students) participated in 8 collaborative problem-solving activities. ANOVAs analysis revealed improvements in declarative and monitoring aspects of SRL with enhanced improvements for initially low SRL students. In Study 2 (ongoing; 108 1st, 3rd, and 5th grade students) participants engage in 12 episodes of pretence and constructional play involving LEGO©, used to stimulate the generation of different genres of texts. Preliminary findings indicate positive uptake of the programme by students and teachers
Importancia de la cartografía dentro del programa Sistema de Información Educativa y Geográfica (SIEG) de la Secretaria de Educación Guerrero
En este trabajo de memoria se da a conocer la Importancia de la Cartografía dentro del Programa Sistema de Información Educativa y Geográfica (SIEG) de la Secretaría de Educación Guerrero. Describo de manera general los antecedentes de la implementación de dicho programa y doy a conocer mi trayectoria describiendo las aportaciones basadas en la formación académica como geógrafo, las cuales sirvieron para el desarrollo de la metodología encausada a la elaboración de cartografía para el sector educativo. Así mismo doy a conocer mi participación en la integración de información de campo, el diseño y confección de diversos tipos de mapas, que fueron necesarios para la toma de decisiones dentro de las diversas áreas de la Secretaría de Educación Guerrero
Sensor Data Fusion using Unscented Kalman Filter for VOR-based Vision Tracking System for Mobile Robots
This paper presents sensor data fusion using Unscented Kalman Filter (UKF) to implement high performance vestibulo-ocular reflex (VOR) based vision tracking system for mobile robots. Information from various sensors is required to be integrated using an efficient sensor fusion algorithm to achieve a continuous and robust vision tracking system. We use data from low cost accelerometer, gyroscope, and encoders to calculate robot motion information. The Unscented Kalman Filter is used as an efficient sensor fusion algorithm. The UKF is an advanced filtering technique which outperforms widely used Extended Kalman Filter (EKF) in many applications. The system is able to compensate for the slip errors by switching between two different UKF models built for slip and no-slip cases. Since the accelerometer error accumulates with time because of the double integration, the system uses accelerometer data only for the slip case UKF model. Using sensor fusion by UKF, the position and orientation of the robot is estimated and is used to rotate the camera mounted on top of the robot towards a fixed target. This concept is derived from the vestibule-ocular reflex (VOR) of the human eye. The experimental results show that the system is able to track the fixed target in various robot motion scenarios including the scenario when an intentional slip is generated during robot navigation
The WaZP galaxy cluster sample of the dark energy survey year 1
We present a new (2+1)D galaxy cluster finder based on photometric redshifts called Wavelet Z Photometric (WaZP) applied to DES first year (Y1A1) data. The results are compared to clusters detected by the South Pole Telescope (SPT) survey and the redMaPPer cluster finder, the latter based on the same photometric data. WaZP searches for clusters in wavelet-based density maps of galaxies selected in photometric redshift space without any assumption on the cluster galaxy populations. The comparison to other cluster samples was performed with a matching algorithm based on angular proximity and redshift difference of the clusters. It led to the development of a new approach to match two optical cluster samples, following an iterative approach to minimize incorrect associations. The WaZP cluster finder applied to DES Y1A1 galaxy survey (1511.13 deg2 up to mi = 23 mag) led to the detection of 60 547 galaxy clusters with redshifts 0.05 <z< 0.9 and richness Ngals ≥ 5. Considering the overlapping regions and redshift ranges between the DES Y1A1 and SPT cluster surveys, all SZ based SPT clusters are recovered by the WaZP sample. The comparison between WaZP and redMaPPer cluster samples showed an excellent overall agreement for clusters with richness Ngals (λ for redMaPPer) greater than 25 (20), with 95 per cent recovery on both directions. Based on the cluster cross-match, we explore the relative fragmentation of the two cluster samples and investigate the possible signatures of unmatched clusters
Birds of a Feather? : Magellan/IMACS spectroscopy of the ultra-faint satellites Grus II, Tucana IV, and Tucana V
We present Magellan/IMACS spectroscopy of three recently discovered ultra-faint Milky Way satellites, Grus II, Tucana IV, and Tucana V. We measure systemic velocities of vhel =- 110.0 0.5 - km s 1 , = - + vhel 15.9 1.7 1.8 - km s 1, and = - - + vhel 36.2 2.2 2.5 - km s 1 for the three objects, respectively. Their large relative velocities demonstrate that the satellites are unrelated despite their close physical proximity. We determine a velocity dispersion for Tuc IV of s = - + 4.3 1.0 1.7 - km s 1 , but we cannot resolve the velocity dispersions of the other two systems. For Gru II, we place an upper limit (90% confidence) on the dispersion of σ < 1.9 - km s 1, and for Tuc V, we do not obtain any useful limits. All three satellites have metallicities below [Fe H 2.1 ] = - , but none has a detectable metallicity spread. We determine proper motions for each satellite based on Gaia astrometry and compute their orbits around the Milky Way. Gru II is on a tightly bound orbit with a pericenter of - + 25 7 6 kpc and orbital eccentricity of - + 0.45 0.05 0.08. Tuc V likely has an apocenter beyond 100 kpc and could be approaching the Milky Way for the first time. The current orbit of Tuc IV is similar to that of Gru II, with a pericenter of - + 25 8 11 kpc and an eccentricity of - + 0.36 0.06 0.13. However, a backward integration of the position of Tuc IV demonstrates that it collided with the Large Magellanic Cloud at an impact parameter of 4 kpc ∼120 Myr ago, deflecting its trajectory and possibly altering its internal kinematics. Based on their sizes, masses, and metallicities, we classify Gru II and Tuc IV as likely dwarf galaxies, but the nature of Tuc V remains uncertain
Photoluminescence-free photoreflectance spectra using dual frequency modulation
The following article appeared in Journal of Applied Physics 102.9 (2007): 093507 and may be found at https://aip.scitation.org/doi/10.1063/1.2802991Photoreflectance (PR) spectra are usually obtained by measuring the relative change on the reflectivity of a semiconducting sample induced by a chopped laser beam. The laser beam can also produce photoluminescence (PL) emission at the sample surface which, detected at its same frequency, could appear as an offset distorting the PR spectrum. This parasitic and intrinsically noisy PL signal, not easily discriminated electronically nor optically filtered, can become the dominant part of the PR spectrum at low sample temperatures, hiding spectrum features under its associated noise, or even avoiding data acquisition. An alternative method for PL signal discrimination is proposed in this work, using a different chopping frequency for each light beam: PL and reflected signals will appear each one at its own chopping frequency, while PR signal will be detected at its frequency sum, allowing signal separation by frequency. Both experimental setups are compared using a highly luminescent quantum well structure at low temperatures. While the standard setup suffers the PL limitation, the proposed method overcomes this constraint, allowing good quality spectra to be measured at temperatures as low as 12
Revisiting the mechanical limited-slip differential for high-performance and race car applications
This paper provides a comprehensive revision of the working principles and limitations of the mechanical limited-slip differential (LSD), a passive device used to improve traction capabilities and to extend the performance envelope of high-performance road cars, racing and rally cars. The LSD has been in use for decades. However, according to the authors’ experience, its impact on vehicle dynamics appears to be somewhat neglected in the literature and often misunderstood, especially in the semi-pro racing community. Current research on the subject is usually focused on side aspects and/or on modern control applications such as active differentials and torque-vectoring systems. These state-of-the-art technologies still rely on the same principles of the LSD, which should therefore be fully explained. The authors intend to fill this gap by starting with a comprehensive literature review. Then, an intuitive explanation of the impact of limited slip systems on vehicle behaviour is proposed with simple mathematical models and examples to integrate what seems to be missing. The peculiar shape of the torque-sensitive LSD working zone on the torque bias diagram is explained to an unprecedented level of detail. Real-world application examples are provided, including data recorded on a single-seater racecar integrated with examples based on a virtual model
The leading Ruelle resonances of chaotic maps
The leading Ruelle resonances of typical chaotic maps, the perturbed cat map
and the standard map, are calculated by variation. It is found that, excluding
the resonance associated with the invariant density, the next subleading
resonances are, approximately, the roots of the equation , where
is a positive number which characterizes the amount of stochasticity
of the map. The results are verified by numerical computations, and the
implications to the form factor of the corresponding quantum maps are
discussed.Comment: 5 pages, 4 figures included. To appear in Phys. Rev.
Molecular Characterization and Genome Mechanical Features of Two Newly Isolated Polyvalent Bacteriophages Infecting Pseudomonas syringae pv. garcae
Coffee plants have been targeted by a devastating bacterial disease, a condition known as bacterial blight, caused by the phytopathogen Pseudomonas syringae pv. garcae (Psg). Conventional treatments of coffee plantations affected by the disease involve frequent spraying with copper- and kasugamycin-derived compounds, but they are both highly toxic to the environment and stimulate the appearance of bacterial resistance. Herein, we report the molecular characterization and mechanical features of the genome of two newly isolated (putative polyvalent) lytic phages for Psg. The isolated phages belong to class Caudoviricetes and present a myovirus-like morphotype belonging to the genuses Tequatrovirus (PsgM02F) and Phapecoctavirus (PsgM04F) of the subfamilies Straboviridae (PsgM02F) and Stephanstirmvirinae (PsgM04F), according to recent bacterial viruses' taxonomy, based on their complete genome sequences. The 165,282 bp (PsgM02F) and 151,205 bp (PsgM04F) genomes do not feature any lysogenic-related (integrase) genes and, hence, can safely be assumed to follow a lytic lifestyle. While phage PsgM02F produced a morphogenesis yield of 124 virions per host cell, phage PsgM04F produced only 12 virions per host cell, indicating that they replicate well in Psg with a 50 min latency period. Genome mechanical analyses established a relationship between genome bendability and virion morphogenesis yield within infected host cells
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