64,401 research outputs found
Analyzing equivalalences in discourse: are discourse theory and membership categorization analysis comptatible
Facing a crucial leap from political philosophy to empirical analysis, the approach to discourse analysis that arose in the aftermath of Laclau and Mouffe (1985), and that is currently known as the Essex school of discourse theory (DT), has in recent years repeatedly been accused of suffering from a methodological deficit. This paper examines to what extent membership categorization analysis (MCA), a branch of ethnomethodology that investigates lay actors' situated descriptions-in-context as practical activity, can play a part in rendering poststructuralist DT notions such as articulation and equivalence analytically tangible in empirically observable discourse. Based on a review of Laclau and Mouffe's foundational text as well as on Glynos and Howarth's recent exposition of the framework (2007), it is argued that MCA empirically substantiates many poststructuralist claims about the indeterminacy of signification. However, MCA consistently falters - and willingly so - at the point where DT would articulate emerging equivalences between identity categories as part of a second-order explanatory concept, such as Glynos and Howarth’s notion of political logic. Nevertheless, MCA also contains the kernel of an "endogenous" notion of the political that comes fairly close to DT’s all-pervasive understanding of the concept. To support these arguments, a variety of empirical sources are mobilized, ranging from the transcript of a political talk show, a newspaper report regarding a discrimination case in a dance class, to data drawn from earlier research on the way that minority members are treated by the Belgian criminal justice system
Run Time Approximation of Non-blocking Service Rates for Streaming Systems
Stream processing is a compute paradigm that promises safe and efficient
parallelism. Modern big-data problems are often well suited for stream
processing's throughput-oriented nature. Realization of efficient stream
processing requires monitoring and optimization of multiple communications
links. Most techniques to optimize these links use queueing network models or
network flow models, which require some idea of the actual execution rate of
each independent compute kernel within the system. What we want to know is how
fast can each kernel process data independent of other communicating kernels.
This is known as the "service rate" of the kernel within the queueing
literature. Current approaches to divining service rates are static. Modern
workloads, however, are often dynamic. Shared cloud systems also present
applications with highly dynamic execution environments (multiple users,
hardware migration, etc.). It is therefore desirable to continuously re-tune an
application during run time (online) in response to changing conditions. Our
approach enables online service rate monitoring under most conditions,
obviating the need for reliance on steady state predictions for what are
probably non-steady state phenomena. First, some of the difficulties associated
with online service rate determination are examined. Second, the algorithm to
approximate the online non-blocking service rate is described. Lastly, the
algorithm is implemented within the open source RaftLib framework for
validation using a simple microbenchmark as well as two full streaming
applications.Comment: technical repor
A Labeled Graph Kernel for Relationship Extraction
In this paper, we propose an approach for Relationship Extraction (RE) based
on labeled graph kernels. The kernel we propose is a particularization of a
random walk kernel that exploits two properties previously studied in the RE
literature: (i) the words between the candidate entities or connecting them in
a syntactic representation are particularly likely to carry information
regarding the relationship; and (ii) combining information from distinct
sources in a kernel may help the RE system make better decisions. We performed
experiments on a dataset of protein-protein interactions and the results show
that our approach obtains effectiveness values that are comparable with the
state-of-the art kernel methods. Moreover, our approach is able to outperform
the state-of-the-art kernels when combined with other kernel methods
Coexistence and Survival in Conservative Lotka-Volterra Networks
Analyzing coexistence and survival scenarios of Lotka-Volterra (LV) networks in which the total biomass is conserved is of vital importance for the characterization of long-term dynamics of ecological communities. Here, we introduce a classification scheme for coexistence scenarios in these conservative LV models and quantify the extinction process by employing the Pfaffian of the network's interaction matrix. We illustrate our findings on global stability properties for general systems of four and five species and find a generalized scaling law for the extinction time
Can we identify non-stationary dynamics of trial-to-trial variability?"
Identifying sources of the apparent variability in non-stationary scenarios is a fundamental problem in many biological data analysis settings. For instance, neurophysiological responses to the same task often vary from each repetition of the same experiment (trial) to the next. The origin and functional role of this observed variability is one of the fundamental questions in neuroscience. The nature of such trial-to-trial dynamics however remains largely elusive to current data analysis approaches. A range of strategies have been proposed in modalities such as electro-encephalography but gaining a fundamental insight into latent sources of trial-to-trial variability in neural recordings is still a major challenge. In this paper, we present a proof-of-concept study to the analysis of trial-to-trial variability dynamics founded on non-autonomous dynamical systems. At this initial stage, we evaluate the capacity of a simple statistic based on the behaviour of trajectories in classification settings, the trajectory coherence, in order to identify trial-to-trial dynamics. First, we derive the conditions leading to observable changes in datasets generated by a compact dynamical system (the Duffing equation). This canonical system plays the role of a ubiquitous model of non-stationary supervised classification problems. Second, we estimate the coherence of class-trajectories in empirically reconstructed space of system states. We show how this analysis can discern variations attributable to non-autonomous deterministic processes from stochastic fluctuations. The analyses are benchmarked using simulated and two different real datasets which have been shown to exhibit attractor dynamics. As an illustrative example, we focused on the analysis of the rat's frontal cortex ensemble dynamics during a decision-making task. Results suggest that, in line with recent hypotheses, rather than internal noise, it is the deterministic trend which most likely underlies the observed trial-to-trial variability. Thus, the empirical tool developed within this study potentially allows us to infer the source of variability in in-vivo neural recordings
Learning Convolutional Text Representations for Visual Question Answering
Visual question answering is a recently proposed artificial intelligence task
that requires a deep understanding of both images and texts. In deep learning,
images are typically modeled through convolutional neural networks, and texts
are typically modeled through recurrent neural networks. While the requirement
for modeling images is similar to traditional computer vision tasks, such as
object recognition and image classification, visual question answering raises a
different need for textual representation as compared to other natural language
processing tasks. In this work, we perform a detailed analysis on natural
language questions in visual question answering. Based on the analysis, we
propose to rely on convolutional neural networks for learning textual
representations. By exploring the various properties of convolutional neural
networks specialized for text data, such as width and depth, we present our
"CNN Inception + Gate" model. We show that our model improves question
representations and thus the overall accuracy of visual question answering
models. We also show that the text representation requirement in visual
question answering is more complicated and comprehensive than that in
conventional natural language processing tasks, making it a better task to
evaluate textual representation methods. Shallow models like fastText, which
can obtain comparable results with deep learning models in tasks like text
classification, are not suitable in visual question answering.Comment: Conference paper at SDM 2018. https://github.com/divelab/sva
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