1,112 research outputs found
Toward the validation of a literature classroom intervention to foster adolescents’ insight into human nature:an iterative design process
We report on the design process of a literature classroom intervention for 15-year-old students in the Netherlands, which aimed to foster their insight into human nature―insight into themselves, fictional others, and real-world others. Starting from a model of transformative reading, an exploration of the educational context, and a review of previous intervention studies, we designed an intervention in an iterative process. We evaluated the validity and practicality of two versions of the intervention. From teacher and student data, we concluded that the validity and practicality of the first version were suboptimal and identified various suggestions for improvement. In a second iteration, the initial design principles were reoperationalized. Based on these eoperationalized principles, we designed a second version of the intervention, which was found to be sufficiently valid and practical. In addition, the second iteration led to specifiying the initial design principles, by formulating subprinciples for operationalization in the classroom. All in all, this study demonstrates that an iterative design process is needed to arrive at a valid and practical intervention, and that this process may have the potential to further specify initial design principles
Socially Optimal Mining Pools
Mining for Bitcoins is a high-risk high-reward activity. Miners, seeking to
reduce their variance and earn steadier rewards, collaborate in pooling
strategies where they jointly mine for Bitcoins. Whenever some pool participant
is successful, the earned rewards are appropriately split among all pool
participants. Currently a dozen of different pooling strategies (i.e., methods
for distributing the rewards) are in use for Bitcoin mining.
We here propose a formal model of utility and social welfare for Bitcoin
mining (and analogous mining systems) based on the theory of discounted
expected utility, and next study pooling strategies that maximize the social
welfare of miners. Our main result shows that one of the pooling strategies
actually employed in practice--the so-called geometric pay pool--achieves the
optimal steady-state utility for miners when its parameters are set
appropriately.
Our results apply not only to Bitcoin mining pools, but any other form of
pooled mining or crowdsourcing computations where the participants engage in
repeated random trials towards a common goal, and where "partial" solutions can
be efficiently verified
Envy, Regret, and Social Welfare Loss
Incentive compatibility (IC) is a desirable property for any auction mechanism, including those used in online advertising. However, in real world applications practical constraints and complex environments often result in mechanisms that lack incentive compatibility. Recently, several papers investigated the problem of deploying black-box statistical tests to determine if an auction mechanism is incentive compatible by using the notion of IC-Regret that measures the regret of a truthful bidder. Unfortunately, most of those methods are computationally intensive, since they require the execution of many counterfactual experiments. In this work, we show that similar results can be obtained using the notion of IC-Envy. The advantage of IC-Envy is its efficiency: it can be computed using only the auction's outcome. In particular, we focus on position auctions. For position auctions, we show that for a large class of pricing schemes (which includes e.g. VCG and GSP), IC-Envy ≥ IC-Regret (and IC-Envy = IC-Regret under mild supplementary conditions). Our theoretical results are completed showing that, in the position auction environment, IC-Envy can be used to bound the loss in social welfare due to the advertiser untruthful behavior. Finally, we show experimentally that IC-Envy can be used as a feature to predict IC-Regret in settings not covered by the theoretical results. In particular, using IC-Envy yields better results than training models using only price and value features
Structured Traversal of Search Trees in Constraint-logic Object-oriented Programming
In this paper, we propose an explicit, non-strict representation of search
trees in constraint-logic object-oriented programming. Our search tree
representation includes both the non-deterministic and deterministic behaviour
during execution of an application. Introducing such a representation
facilitates the use of various search strategies. In order to demonstrate the
applicability of our approach, we incorporate explicit search trees into the
virtual machine of the constraint-logic object-oriented programming language
Muli. We then exemplarily implement three search algorithms that traverse the
search tree on-demand: depth-first search, breadth-first search, and iterative
deepening depth-first search. In particular, the last two strategies allow for
a complete search, which is novel in constraint-logic object-oriented
programming and highlights our main contribution. Finally, we compare the
implemented strategies using several benchmarks.Comment: Part of DECLARE 19 proceeding
Pulsational line profile variation of the roAp star HR 3831
We report the first comprehensive investigation of the line profile variation
caused by non-radial pulsation in a magnetic oscillating chemically peculiar
star. Spectrum variation of the well-known roAp star HR 3831 is detected using
very high-resolution high signal-to-noise spectroscopic time-series
observations and are followed through the whole rotation cycle of the star. We
confirm outstanding diversity of pulsational behaviour of different lines in
the HR 3831 spectrum and attribute this phenomenon to an interplay between
extreme vertical chemical inhomogeneity of the HR 3831 atmosphere and a running
pulsation wave, propagating towards the upper photospheric layers with
increasing amplitude. Rapid profile variation of the NdIII 6145 A line is
characterized by measuring changes of its equivalent width and the first three
moments. We demonstrate that rotational modulation of the radial velocity
oscillations cannot be fully explained by an oblique axisymmetric dipole
(ell=1, m=0) mode, implied by the classical oblique pulsator model of roAp
stars. Pulsational variation of the higher moments reveal substantial
contribution of the high-order (ell=3) spherical harmonics which appear due to
distortion of pulsations in HR 3831 by the global magnetic field. We interpret
observations with a novel numerical model of the pulsational variation and
rotational modulation of the line profile moments in roAp stars. The comparison
between observed and computed amplitudes and phases of the radial velocity and
line width variation is used to establish parameters of the oblique pulsator
model of HR 3831. Furthermore, definite detection of pulsational variation in
lines of light and iron-peak elements enables the first 3-D mapping of
pulsations in non-radially oscillating star.Comment: 21 pages, 11 figures; accepted by A&
The chaperone protein clusterin may serve as a cerebrospinal fluid biomarker for chronic spinal cord disorders in the dog
Chronic spinal cord dysfunction occurs in dogs as a consequence of diverse aetiologies, including long-standing spinal cord compression and insidious neurodegenerative conditions. One such neurodegenerative condition is canine degenerative myelopathy (DM), which clinically is a challenge to differentiate from other chronic spinal cord conditions. Although the clinical diagnosis of DM can be strengthened by the identification of the Sod1 mutations that are observed in affected dogs, genetic analysis alone is insufficient to provide a definitive diagnosis. There is a requirement to identify biomarkers that can differentiate conditions with a similar clinical presentation, thus facilitating patient diagnostic and management strategies. A comparison of the cerebrospinal fluid (CSF) protein gel electrophoresis profile between idiopathic epilepsy (IE) and DM identified a protein band that was more prominent in DM. This band was subsequently found to contain a multifunctional protein clusterin (apolipoprotein J) that is protective against endoplasmic reticulum (ER) stress-mediated apoptosis, oxidative stress, and also serves as an extracellular chaperone influencing protein aggregation. Western blot analysis of CSF clusterin confirmed elevated levels in DM compared to IE (p < 0.05). Analysis of spinal cord tissue from DM and control material found that clusterin expression was evident in neurons and that the clusterin mRNA levels from tissue extracts were elevated in DM compared to the control. The plasma clusterin levels was comparable between these groups. However, a comparison of clusterin CSF levels in a number of neurological conditions found that clusterin was elevated in both DM and chronic intervertebral disc disease (cIVDD) but not in meningoencephalitis and IE. These findings indicate that clusterin may potentially serve as a marker for chronic spinal cord disease in the dog; however, additional markers are required to differentiate DM from a concurrent condition such as cIVDD
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