16,286 research outputs found
Signatures of extra dimensions in gravitational waves
Considering gravitational waves propagating on the most general
4+N-dimensional space-time, we investigate the effects due to the N extra
dimensions on the four-dimensional waves. All wave equations are derived in
general and discussed. On Minkowski4 times an arbitrary Ricci-flat compact
manifold, we find: a massless wave with an additional polarization, the
breathing mode, and extra waves with high frequencies fixed by Kaluza-Klein
masses. We discuss whether these two effects could be observed.Comment: v1: 21 pages + appendices, comments welcome! v2: few minor additions;
v3: minor mistake corrected in the warped case, no impact on the main
results, appendix A.2 modifie
A non-projective greedy dependency parser with bidirectional LSTMs
The LyS-FASTPARSE team presents BIST-COVINGTON, a neural implementation of
the Covington (2001) algorithm for non-projective dependency parsing. The
bidirectional LSTM approach by Kipperwasser and Goldberg (2016) is used to
train a greedy parser with a dynamic oracle to mitigate error propagation. The
model participated in the CoNLL 2017 UD Shared Task. In spite of not using any
ensemble methods and using the baseline segmentation and PoS tagging, the
parser obtained good results on both macro-average LAS and UAS in the big
treebanks category (55 languages), ranking 7th out of 33 teams. In the all
treebanks category (LAS and UAS) we ranked 16th and 12th. The gap between the
all and big categories is mainly due to the poor performance on four parallel
PUD treebanks, suggesting that some `suffixed' treebanks (e.g. Spanish-AnCora)
perform poorly on cross-treebank settings, which does not occur with the
corresponding `unsuffixed' treebank (e.g. Spanish). By changing that, we obtain
the 11th best LAS among all runs (official and unofficial). The code is made
available at https://github.com/CoNLL-UD-2017/LyS-FASTPARSEComment: 12 pages, 2 figures, 5 table
Do Quasi-Hyperbolic Preferences Explain Academic Procrastination? An Empirical Evaluation
Traditional neoclassical thought fails to explain questions such as problems of self-control. Behavioural
economics have explained these matters on the basis of the intertemporal preferences of individuals
and, specifically, the so-called (β, δ) model which emphasises present bias. This opens the way
to the analysis of new situations in which people can adopt incorrect indecisions that make it necessary
for the government to intervene. The literature which has developed the (β, δ) model and its implications
has generated a categorisation of people that is widely used but which lacks a systematic empirical
evaluation. It is important to value the need for this public action. In this article, we develop a
method which makes it possible to verify the main implications that this model has to explain the
procrastination of university students. Using an experimental time discount task with real monetary
incentives, we estimate the students’ β and δ parameters and we analyse their correlation with their
answers to a series of questions concerning how they plan to study for an exam. The results are ambiguous
given that they back some of the model’s conclusions but reject others, including a number of
the most basic ones, such as the relation between present biases and some of the categories of people,
these being essential to predict their behaviour
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