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Exposing piaget's scheme: Empirical evidence for the ontogenesis of coordination in learning a mathematical concept
The combination of two methodological resources-natural-user interfaces (NUI) and multimodal learning analytics (MMLA)-is creating opportunities for educational researchers to empirically evaluate seminal models for the hypothetical emergence of concepts from situated sensorimotor activity. 76 participants (9-14 yo) solved tablet-based non-symbolic manipulation tasks designed to foster grounded meanings for the mathematical concept of proportional equivalence. Data gathered in task-based semi-structured clinical interviews included action logging, eye-gaze tracking, and videography. Successful task performance coincided with spontaneous appearance of stable dynamical gaze-path patterns soon followed by multimodal articulation of strategy. Significantly, gaze patterns included uncued non-salient screen locations. We present cumulative results to argue that these 'attentional anchors' mediated participants' problem solving. We interpret the findings as enabling us to revisit, support, refine, and elaborate on central claims of Piaget's theory of genetic epistemology and in particular his insistence on the role of situated motor-action coordination in the process of reflective abstraction
“The Criminal Class” -- Long Term Social Health Consequences of Mass Incarceration
The United States has been experiencing a dramatic rise in prison and jail populations since the 1980s, which has resulted in a much higher population of individuals reintegrating into society with a criminal record. This brand has been identified to cause several negative effects on one’s social and economic capacities, with these effects being exacerbated on target populations such as minorities. Research on limitations and challenges placed on individuals with a criminal record were compared with World Health Organization standards for social determinants of health, to determine the potential for long-term health consequences as a result of society’s social consequences for reintegrated criminals. A major failure of nearly every category for focus in social determinants of health was identified, ranging from social standing, lifestyle stress, unemployment and economic opportunities, and implications on social support for children. Multiple sources of academic work would culminate towards a strong implication that a felony sentence, criminal record, or extended period of incarceration, has direct and immediate consequences on one’s ability to lead a long, healthy, and fulfilling life. Wide-scale policy reform would seem essential to curb any unforeseen long-term consequences of these findings
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Eye-tracking the emergence of attentional anchors in a mathematics learning tablet activity
Little is known about micro-processes by which sensorimotor interaction gives rise to conceptual development. Per embodiment theory, these micro-processes are mediated by dynamical attentional structures. Accordingly this study investigated eye-gaze behaviors during engagement in solving tablet-based bimanual manipulation tasks designed to foster proportional reasoning. Seventy-six elementary- and vocational-school students (9-15 yo) participated in individual task-based clinical interviews. Data gathered included action-logging, eye-tracking, and videography. Analyses revealed the emergence of stable eye-path gaze patterns contemporaneous with first enactments of effective manipulation and prior to verbal articulations of manipulation strategies. Characteristic gaze patterns included consistent or recurring attention to screen locations that bore non-salient stimuli or no stimuli at all yet bore invariant geometric relations to dynamical salient features. Arguably, this research validates empirically hypothetical constructs from constructivism, particularly reflective abstraction
Thermal X-Ray Pulses Resulting From Pulsar Glitches
The non-spherically symmetric transport equations and exact thermal evolution
model are used to calculate the transient thermal response to pulsars. The
three possible ways of energy release originated from glitches, namely the
`shell', `ring' and `spot' cases are compared. The X-ray light curves resulting
from the thermal response to the glitches are calculated. Only the `spot' case
and the `ring' case are considered because the `shell' case does not produce
significant modulative X-rays. The magnetic field () effect, the
relativistic light bending effect and the rotational effect on the photons
being emitted in a finite region are considered. Various sets of parameters
result in different evolution patterns of light curves. We find that this
modulated thermal X-ray radiation resulting from glitches may provide some
useful constraints on glitch models.Comment: 48 pages, 20 figures, submitted to Ap
Quantum Drag Forces on a Sphere Moving Through a Rarefied Gas
As an application of quantum fluid mechanics, we consider the drag force
exerted on a sphere by an ultra-dilute gas. Quantum mechanical diffraction
scattering theory enters in that regime wherein the mean free path of a
molecule in the gas is large compared with the sphere radius. The drag force is
computed in a model specified by the ``sticking fraction'' of events in which a
gaseous molecule is adsorbed by the spherical surface. Classical inelastic
scattering theory is shown to be inadequate for physically reasonable sticking
fraction values. The quantum mechanical scattering drag force is exhibited
theoretically and compared with experimental data.Comment: 5 pages no figure
Viscous Effects on Impact Probes in a Subsonic Rarified Gas Flow
The problem of time response of pressure gaging systems used with low density flows has been discussed in Ref ]4, and the effect of outgassing on pressure magnitudes was indicated in the same reference. Briefly, gases or vapors adhering to the internal walls of the pressure gaging system behave like gas sources and produce a pressure rise in the gage system which has no relation to the external flow. The effect can also occur in the reverse direction, with "in-gassing" or the action of an effective sink in the gage system as gases entering through the probe orifice are adsorbed to the walls. For given surface conditions, the magnitude of the pressure error to be expected due to out-gassing depends on the dimensions of the probe system. In the present tests, it was desirable to use the smallest possible probe to yield the lowest possible Reynolds number. The lower limit on size was fixed by outgassing effects, evaluated by the following procedure. 2.0 PROCEDURE The pumping system was adjusted to give a pressure, measured at the reservoir, of 9 microns Hg with no flow into the wind tunnel. The upstream metering valve was then opened and the air flow rate adjusted to give a pressure of 100 microns in the reservoir under steady flow conditions, The pressure read by one of the impact tubes, inserted into the flow, was measured. The upstream metering valve was then closed rapid)y, and the reservoir pressure, p0, and the impact probe pressure, Pj, were measured simultaneously at definite time intervals. Another probe was inserted into the flow and the procedure repeated, until the pressure-time data had been obtained for each probe investigated. The results for a series of tests Involving probe Nos.l, 2 and 3 are shown on HYD 2616 300 RESULTS From HYD 2616, It is clear that the smallest probe (No.3) requires the longest time to reach equilibrium. After a sufficient time has elapsed (about 180 seconds), this probe read the same, within the accuracy of measurement, as the other two, When a similar experiment was performed utilizing a probe which was one-half the size of probe No.2, it indicated a pressure, after 180 seconds, which was almost 10 microns Hg higher than the other probes. Accordingly, only probe Nos. 1, 2, 3 and 4 were employed in the experiments, and a time of at least 180 seconds was allowed to elapse between a change of setting and the reading of the instruments
Thomas-Fermi Calculations of Atoms and Matter in Magnetic Neutron Stars II: Finite Temperature Effects
We present numerical calculations of the equation of state for dense matter
in high magnetic fields, using a temperature dependent Thomas-Fermi theory with
a magnetic field that takes all Landau levels into account. Free energies for
atoms and matter are also calculated as well as profiles of the electron
density as a function of distance from the atomic nucleus for representative
values of the magnetic field strength, total matter density, and temperature.
The Landau shell structure, which is so prominent in cold dense matter in high
magnetic fields, is still clearly present at finite temperature as long as it
is less than approximately one tenth of the cyclotron energy. This structure is
reflected in an oscillatory behaviour of the equation of state and other
thermodynamic properties of dense matter and hence also in profiles of the
density and pressure as functions of depth in the surface layers of magnetic
neutron stars. These oscillations are completely smoothed out by thermal
effects at temperatures of the order of the cyclotron energy or higher.Comment: 37 pages, 17 figures included, submitted to Ap
Background Measurements in the Gran Sasso Underground Laboratory
The gamma background flux below 3000 keV in the Laboratori Nazionali del Gran
Sasso (LNGS), Italy, has been measured using a 3" diameter NaI(Tl) detector at
different underground positions: In hall A, hall B, the interferometer tunnel,
and inside the Large Volume Detector (LVD). The integrated flux is 0.3--0.4
scm at the first three locations, and is lower by two orders of
magnitude inside LVD. With the help of Monte Carlo simulations for every
location, the contribution of the individual primordial isotopes to the
background has been determined. Using an 11" diameter NaI(Tl) detector, the
background neutron flux in the LNGS interferometer tunnel has been estimated.
Within the uncertainties, the result agrees with those from other neutron
measurements in the main halls.Comment: 6 pages, 6 figures, accepted versio
Adsorption of colloidal particles in the presence of external field
We present a new class of sequential adsorption models in which the adsorbing
particles reach the surface following an inclined direction (shadow models).
Capillary electrophoresis, adsorption in the presence of a shear or on an
inclined substrate are physical manifestations of these models. Numerical
simulations are carried out to show how the new adsorption mechanisms are
responsible for the formation of more ordered adsorbed layers and have
important implications in the kinetics, in particular modifying the jamming
limit.Comment: LaTex file, 3 figures available upon request, to appear in
Phys.Rev.Let
Temperature distribution in magnetized neutron star crusts
We investigate the influence of different magnetic field configurations on
the temperature distribution in neutron star crusts. We consider axisymmetric
dipolar fields which are either restricted to the stellar crust, ``crustal
fields'', or allowed to penetrate the core, ``core fields''. By integrating the
two-dimensional heat transport equation in the crust, taking into account the
classical (Larmor) anisotropy of the heat conductivity, we obtain the crustal
temperature distribution, assuming an isothermal core. Including quantum
magnetic field effects in the envelope as a boundary condition, we deduce the
corresponding surface temperature distributions. We find that core fields
result in practically isothermal crusts unless the surface field strength is
well above G while for crustal fields with surface strength above a
few times G significant deviations from isothermality occur at core
temperatures inferior or equal to K. At the stellar surface, the cold
equatorial region produced by the quantum suppression of heat transport
perpendicular to the field in the envelope, present for both core and crustal
fields, is significantly extended by the classical suppression at higher
densities in the case of crustal fields. This can result, for crustal fields,
in two small warm polar regions which will have observational consequences: the
neutron star has a small effective thermally emitting area and the X-ray pulse
profiles are expected to have a distinctively different shape compared to the
case of a neutron star with a core field. These features, when compared with
X-ray data on thermal emission of young cooling neutron stars, will open a way
to provide observational evidence in favor, or against, the two radically
different configurations of crustal or core magnetic fields.Comment: 10 pages, 10 figures, submitted to A&
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