782 research outputs found
Test anxiety, working memory, and cognitive performance: Supportive effects of sequential demands
Substantial evidence suggests that test anxiety is associated with poor performance in complex tasks. Based on the differentiation of coordinative and sequential demands on working memory (Mayr & Kliegl, 1993), two studies examined the effects of sequential demands on the relationship between test anxiety and cognitive performance. Both studies found that high sequential demands had beneficial effects on the speed and accuracy of the performance of test-anxious participants. It is suggested that the more frequent memory updates associated with high sequential demands may represent external processing aids that compensate for the restricted memory capacity of individuals with high test anxiet
Circumstellar Disks revealed by / Flux Variation Gradients
The variability of young stellar objects (YSO) changes their brightness and
color preventing a proper classification in traditional color-color and color
magnitude diagrams. We have explored the feasibility of the flux variation
gradient (FVG) method for YSOs, using and band monitoring data of the
star forming region RCW\,38 obtained at the University Observatory Bochum in
Chile. Simultaneous multi-epoch flux measurements follow a linear relation
for almost all YSOs with large variability
amplitude. The slope gives the mean color temperature of
the varying component. Because is hotter than the dust sublimation
temperature, we have tentatively assigned it to stellar variations. If the
gradient does not meet the origin of the flux-flux diagram, an additional non-
or less-varying component may be required. If the variability amplitude is
larger at the shorter wavelength, e.g. , this component is cooler
than the star (e.g. a circumstellar disk); vice versa, if , the
component is hotter like a scattering halo or even a companion star. We here
present examples of two YSOs, where the FVG implies the presence of a
circumstellar disk; this finding is consistent with additional data at and
. One YSO shows a clear -band excess in the color-color diagram,
while the significance of a -excess in the other YSO depends on the
measurement epoch. Disentangling the contributions of star and disk it turns
out that the two YSOs have huge variability amplitudes (\,mag). The
FVG analysis is a powerful complementary tool to analyze the varying
components of YSOs and worth further exploration of monitoring data at other
wavelengths.Comment: 5 pages, 5 figures, accepted for publication in Astronomy and
Astrophysic
The broad-line region and dust torus size of the Seyfert 1 galaxy PGC50427
We present the results of a three years monitoring campaigns of the type-1 active galactic nucleus (AGN) PGC50427. Through the use of
Photometric Reverberation Mapping with broad and narrow band filters, we
determine the size of the broad-line emitting region by measuring the time
delay between the variability of the continuum and the H emission line.
The H emission line responds to blue continuum variations with an
average rest frame lag of days. Using single epoch spectroscopy
we determined a broad-line H velocity width of 1020 km s and in
combination with the rest frame lag and adoption a geometric scaling factor , we calculate a black hole mass of . Using the flux variation gradient method, we separate the host
galaxy contribution from that of the AGN to calculate the rest frame 5100\AA~
luminosity at the time of our monitoring campaign. The rest frame lag and the
host-subtracted luminosity permit us to derive the position of PGC50427 in the
BLR size -- AGN luminosity diagram, which is remarkably close to the
theoretically expected relation of . The simultaneous
optical and NIR ( and ) observations allow us to determine the size
of the dust torus through the use of dust reverberation mapping method. We find
that the hot dust emission () lags the optical variations with an
average rest frame lag of days. The dust reverberation radius
and the nuclear NIR luminosity permit us to derive the position of PGC50427 on
the known diagram. The simultaneus observations for the
broad-line region and dust thermal emission demonstrate that the innermost dust
torus is located outside the BLR in PGC50427, supporting the unified scheme for
AGNs. (Abstract shortened, see the manuscript.)Comment: 11 pages, 23 figures, accepted for publication in Astronomy and
Astrophysic
Business Models for Internet of Things Platforms: Empirical Development of a Taxonomy and Archetypes
A wide range of Internet of Things platform providers operate diverse business models to cater for the manifold requirements of the IoT. This paper contributes to a more precise understanding of IoT platforms as an essential building block of the IoT based on the characteristics of its business models. Even though research listing technological dimensions according to which IoT platforms differ, they have neither been systematically derived nor been linked to the business model concept. In turn, they lack descriptive power on the heterogeneous value creation mechanisms of the platform providers. Within our research, we first analyzed 195 IoT platforms and systemically developed a taxonomy allowing the characterization of IoT platform business models. Second, based on this taxonomy, we identified nine archetypes of IoT platform business models and illustrated typical combinations of business model characteristics. Equipped with such an understanding, practice and research can analyze existing IoT platforms more accurately
Power-law tail distributions and nonergodicity
We establish an explicit correspondence between ergodicity breaking in a
system described by power-law tail distributions and the divergence of the
moments of these distributions.Comment: 4 pages, 1 figure, corrected typo
Developing Special Education Advocates: What Changes during an Advocacy Training Program?
Background: Special education advocacy trainings, such as the Volunteer Advocacy Project (VAP), have the goal of training advocates who can eventually support families in accessing needed services for students with disabilities. In addition to the training goal of increasing participants\u27 special education knowledge and advocacy comfort, it is unknown if the VAP improves other participant outcomes related to later advocacy.
Specific Aims: In this study, we asked: (1) Do VAP participants improve from preā to postātest on knowledge and advocacy comfort, as well as on role identity, involvement in the disability community, and empowerment?; (2) Do participants\u27 roles and levels of education moderate improvements in these outcomes?; and (3) Do participants who are differentially higher or lower on any of these variables at the preātest show greater improvement from preā to postātest on one or all other variables?
Method: Participants included 70 graduates of the VAP from 2014 to 2016. These participants completed preātest and postātest assessments with measures on: special education knowledge, advocacy comfort, role identity, involvement, and empowerment.
Findings: Results showed significant change in knowledge, comfort, involvement, and empowerment from preātest to postātest. Only level of education significantly moderated the change in role identity from preātest to postātest, with those with high school education increasing their role identity compared to those with a college degree or more. Empowerment was closely related to preātest levels and to change scores for all other variables.
Discussion: Implications for future research and practice are discussed, including the need to better understand moderators of treatment effect and mechanisms of change for advocacy trainings
Neural excitability and sensory input determine intensity perception with opposing directions in initial cortical responses
Perception of sensory information is determined by stimulus features (e.g., intensity) and instantaneous neural states (e.g., excitability). Commonly, it is assumed that both are reflected similarly in evoked brain potentials, that is, larger amplitudes are associated with a stronger percept of a stimulus. We tested this assumption in a somatosensory discrimination task in humans, simultaneously assessing (i) single-trial excitatory post-synaptic currents inferred from short-latency somatosensory evoked potentials (SEPs), (ii) pre-stimulus alpha oscillations (8-13 Hz), and (iii) peripheral nerve measures. Fluctuations of neural excitability shaped the perceived stimulus intensity already during the very first cortical response (at ~20 ms) yet demonstrating opposite neural signatures as compared to the effect of presented stimulus intensity. We reconcile this discrepancy via a common framework based on the modulation of electro-chemical membrane gradients linking neural states and responses, which calls for reconsidering conventional interpretations of brain potential magnitudes in stimulus intensity encoding
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