175 research outputs found
The use of speaker correlation information for automatic speech recognition
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (p. 171-179).by Timothy J. Hazen.Ph.D
On the Social and Technical Challenges of Web Search Autosuggestion Moderation
Past research shows that users benefit from systems that support them in
their writing and exploration tasks. The autosuggestion feature of Web search
engines is an example of such a system: It helps users in formulating their
queries by offering a list of suggestions as they type. Autosuggestions are
typically generated by machine learning (ML) systems trained on a corpus of
search logs and document representations. Such automated methods can become
prone to issues that result in problematic suggestions that are biased, racist,
sexist or in other ways inappropriate. While current search engines have become
increasingly proficient at suppressing such problematic suggestions, there are
still persistent issues that remain. In this paper, we reflect on past efforts
and on why certain issues still linger by covering explored solutions along a
prototypical pipeline for identifying, detecting, and addressing problematic
autosuggestions. To showcase their complexity, we discuss several dimensions of
problematic suggestions, difficult issues along the pipeline, and why our
discussion applies to the increasing number of applications beyond web search
that implement similar textual suggestion features. By outlining persistent
social and technical challenges in moderating web search suggestions, we
provide a renewed call for action.Comment: 17 Pages, 4 images displayed within 3 latex figure
Open-vocabulary spoken utterance retrieval using confusion networks
This paper presents a novel approach to open-vocabulary spoken utterance retrieval using confusion networks. If out-of-vocabulary (OOV) words are present in queries and the corpus, word-based indexing will not be sufficient. For this problem, we apply phone confusion networks and combine them with word confusion networks. With this approach, we can generate a more compact index table that enables robust keyword matching compared with typical lattice-based methods. In the retrieval experiments with speech recordings in MIT lecture corpus, our method using phone confusion networks outperformed lattice-based methods especially for OOV queries
Period and chemical evolution of SC stars
The SC and CS stars are thermal-pulsing AGB stars with C/O ratio close to
unity. Within this small group, the Mira variable BH Cru recently evolved from
spectral type SC (showing ZrO bands) to CS (showing weak C2). Wavelet analysis
shows that the spectral evolution was accompanied by a dramatic period
increase, from 420 to 540 days, indicating an expanding radius. The pulsation
amplitude also increased. Old photographic plates are used to establish that
the period before 1940 was around 490 days. Chemical models indicate that the
spectral changes were caused by a decrease in stellar temperature, related to
the increasing radius. There is no evidence for a change in C/O ratio. The
evolution in BH Cru is unlikely to be related to an on-going thermal pulse.
Periods of the other SC and CS stars, including nine new periods, are
determined. A second SC star, LX Cyg, also shows evidence for a large increase
in period, and one further star shows a period inconsistent with a previous
determination. Mira periods may be intrinsically unstable for C/O ~ 1; possibly
because of a feedback between the molecular opacities, pulsation amplitude, and
period. LRS spectra of 6 SC stars suggest a feature at wavelength > 15 micron,
which resembles one recently attributed to the iron-sulfide troilite. Chemical
models predict a large abundance of FeS in SC stars, in agreement with the
proposed association.Comment: 14 pages, 20 figures. MNRAS, 2004, accepted for publication. Janet
Mattei, one of the authors, died on 22 March, 2004. This paper is dedicated
to her memor
An Abundant Dysfunctional Apolipoprotein A1 in Human Atheroma
Recent studies have indicated that high-density lipoproteins (HDLs) and their major structural protein, apolipoprotein A1 (apoA1), recovered from human atheroma are dysfunctional and are extensively oxidized by myeloperoxidase (MPO). In vitro oxidation of either apoA1 or HDL particles by MPO impairs their cholesterol acceptor function. Here, using phage display affinity maturation, we developed a high-affinity monoclonal antibody that specifically recognizes both apoA1 and HDL that have been modified by the MPO-H2O2-Cl− system. An oxindolyl alanine (2-OH-Trp) moiety at Trp72 of apoA1 is the immunogenic epitope. Mutagenesis studies confirmed a critical role for apoA1 Trp72 in MPO-mediated inhibition of the ATP-binding cassette transporter A1 (ABCA1)-dependent cholesterol acceptor activity of apoA1 in vitro and in vivo. ApoA1 containing a 2-OH-Trp72 group (oxTrp72-apoA1) is in low abundance within the circulation but accounts for 20% of the apoA1 in atherosclerosis-laden arteries. OxTrp72-apoA1 recovered from human atheroma or plasma is lipid poor, virtually devoid of cholesterol acceptor activity and demonstrated both a potent proinflammatory activity on endothelial cells and an impaired HDL biogenesis activity in vivo. Elevated oxTrp72-apoA1 levels in subjects presenting to a cardiology clinic (n = 627) were associated with increased cardiovascular disease risk. Circulating oxTrp72-apoA1 levels may serve as a way to monitor a proatherogenic process in the artery wall
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