9,109 research outputs found
Generative Modelling for Unsupervised Score Calibration
Score calibration enables automatic speaker recognizers to make
cost-effective accept / reject decisions. Traditional calibration requires
supervised data, which is an expensive resource. We propose a 2-component GMM
for unsupervised calibration and demonstrate good performance relative to a
supervised baseline on NIST SRE'10 and SRE'12. A Bayesian analysis demonstrates
that the uncertainty associated with the unsupervised calibration parameter
estimates is surprisingly small.Comment: Accepted for ICASSP 201
The Directed Closure Process in Hybrid Social-Information Networks, with an Analysis of Link Formation on Twitter
It has often been taken as a working assumption that directed links in
information networks are frequently formed by "short-cutting" a two-step path
between the source and the destination -- a kind of implicit "link copying"
analogous to the process of triadic closure in social networks. Despite the
role of this assumption in theoretical models such as preferential attachment,
it has received very little direct empirical investigation. Here we develop a
formalization and methodology for studying this type of directed closure
process, and we provide evidence for its important role in the formation of
links on Twitter. We then analyze a sequence of models designed to capture the
structural phenomena related to directed closure that we observe in the Twitter
data
Non-linear HRV analysis to quantify the effects of intermittent hypoxia using an OSA rat model
© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting /republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksIn this paper, a non-linear HRV analysis was performed to assess fragmentation signatures observed in heartbeat time series after intermittent hypoxia (IH). Three markers quantifying short-term fragmentation levels, PIP, IALS and PSS, were evaluated on R-R interval series obtained in a rat model of recurrent apnea. Through airway obstructions, apnea episodes were periodically simulated in six anesthetized Sprague-Dawley rats. The number of apnea events per hour (AHI index) was varied during the first half of the experiment while apnea episodes lasted 15 s. For the second part, apnea episodes lasted 5, 10 or 15 s, but the AHI index was fixed. Recurrent apnea was repeated for 15-min time intervals in all cases, alternating with basal periods of the same duration. The fragmentation markers were evaluated in segments of 5 minutes, selected at the beginning and end of the experiment. The impact of the heart and breathing rates (HR and BR, respectively) on the parameter estimates was also investigated. The results obtained show a significant increase (from 5 to 10%, p 0.9) between these markers and BR, as well as with the ratio given by HR/BR. Although fragmentation may be impacted by IH, we found that it is highly dependent on HR and BR values and thus, they should be considered during its calculation or used to normalize the fragmentation estimatesPeer ReviewedPostprint (published version
Quantum interference through gated single-molecule junctions
We discuss the general form of the transmission spectrum through a molec-
ular junction in terms of the Green function of the isolated molecule. By
introducing a tight binding method, we are able to translate the Green func-
tion properties into practical graphical rules for assessing beforehand the
possible existence of antiresonances in an energy range for a given choice of
connecting sites. The analysis is exemplified with a benzene molecule under a
hypothetical local gate, which allows one to continuously tune the on-site
energy of single atoms, for various connection topologies and gate positions.Comment: 17 pages, 5 figure
The economic consequences of the spanish Reconquest: The long-term effects of medieval conquest and colonization
This paper shows that a historical process that ended more than five centuries ago, the
Reconquest, is very important to explain Spanish regional economic development down to
the present day. An indicator measuring the rate of Reconquest reveals a heavily negative
effect on current income differences across the Spanish provinces. A main intervening
factor in the impact the Reconquest has had is the concentration of economic and political
power in a few hands, excluding large segments of the population from access to economic
opportunities when Spain entered the industrialization phase. The timing of the effect is
consistent with this argument. A general implication of our analysis is that large frontier
expansions may favor a political equilibrium among the colonizing agents that is biased
toward the elite, creating the conditions for an inegalitarian society, with negative
consequences for long-term economic developmenTUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Network Structure, Efficiency, and Performance in WikiProjects
The internet has enabled collaborations at a scale never before possible, but
the best practices for organizing such large collaborations are still not
clear. Wikipedia is a visible and successful example of such a collaboration
which might offer insight into what makes large-scale, decentralized
collaborations successful. We analyze the relationship between the structural
properties of WikiProject coeditor networks and the performance and efficiency
of those projects. We confirm the existence of an overall
performance-efficiency trade-off, while observing that some projects are higher
than others in both performance and efficiency, suggesting the existence
factors correlating positively with both. Namely, we find an association
between low-degree coeditor networks and both high performance and high
efficiency. We also confirm results seen in previous numerical and small-scale
lab studies: higher performance with less skewed node distributions, and higher
performance with shorter path lengths. We use agent-based models to explore
possible mechanisms for degree-dependent performance and efficiency. We present
a novel local-majority learning strategy designed to satisfy properties of
real-world collaborations. The local-majority strategy as well as a localized
conformity-based strategy both show degree-dependent performance and
efficiency, but in opposite directions, suggesting that these factors depend on
both network structure and learning strategy. Our results suggest possible
benefits to decentralized collaborations made of smaller, more tightly-knit
teams, and that these benefits may be modulated by the particular learning
strategies in use.Comment: 11 pages, 5 figures, to appear in ICWSM 201
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