91,969 research outputs found
Second language learning in the context of MOOCs
Massive Open Online Courses are becoming popular educational vehicles through which universities reach out to non-traditional audiences. Many enrolees hail from other countries and cultures, and struggle to cope with the English language in which these courses are invariably offered. Moreover, most such learners have a strong desire and motivation to extend their knowledge of academic English, particularly in the specific area addressed by the course. Online courses provide a compelling opportunity for domain-specific language learning. They supply a large corpus of interesting linguistic material relevant to a particular area, including supplementary images (slides), audio and video. We contend that this corpus can be automatically analysed, enriched, and transformed into a resource that learners can browse and query in order to extend their ability to understand the language used, and help them express themselves more fluently and eloquently in that domain. To illustrate this idea, an existing online corpus-based language learning tool (FLAX) is applied to a Coursera MOOC entitled Virology 1: How Viruses Work, offered by Columbia University
Finding Person Relations in Image Data of the Internet Archive
The multimedia content in the World Wide Web is rapidly growing and contains
valuable information for many applications in different domains. For this
reason, the Internet Archive initiative has been gathering billions of
time-versioned web pages since the mid-nineties. However, the huge amount of
data is rarely labeled with appropriate metadata and automatic approaches are
required to enable semantic search. Normally, the textual content of the
Internet Archive is used to extract entities and their possible relations
across domains such as politics and entertainment, whereas image and video
content is usually neglected. In this paper, we introduce a system for person
recognition in image content of web news stored in the Internet Archive. Thus,
the system complements entity recognition in text and allows researchers and
analysts to track media coverage and relations of persons more precisely. Based
on a deep learning face recognition approach, we suggest a system that
automatically detects persons of interest and gathers sample material, which is
subsequently used to identify them in the image data of the Internet Archive.
We evaluate the performance of the face recognition system on an appropriate
standard benchmark dataset and demonstrate the feasibility of the approach with
two use cases
Fast and Lean Immutable Multi-Maps on the JVM based on Heterogeneous Hash-Array Mapped Tries
An immutable multi-map is a many-to-many thread-friendly map data structure
with expected fast insert and lookup operations. This data structure is used
for applications processing graphs or many-to-many relations as applied in
static analysis of object-oriented systems. When processing such big data sets
the memory overhead of the data structure encoding itself is a memory usage
bottleneck. Motivated by reuse and type-safety, libraries for Java, Scala and
Clojure typically implement immutable multi-maps by nesting sets as the values
with the keys of a trie map. Like this, based on our measurements the expected
byte overhead for a sparse multi-map per stored entry adds up to around 65B,
which renders it unfeasible to compute with effectively on the JVM.
In this paper we propose a general framework for Hash-Array Mapped Tries on
the JVM which can store type-heterogeneous keys and values: a Heterogeneous
Hash-Array Mapped Trie (HHAMT). Among other applications, this allows for a
highly efficient multi-map encoding by (a) not reserving space for empty value
sets and (b) inlining the values of singleton sets while maintaining a (c)
type-safe API.
We detail the necessary encoding and optimizations to mitigate the overhead
of storing and retrieving heterogeneous data in a hash-trie. Furthermore, we
evaluate HHAMT specifically for the application to multi-maps, comparing them
to state-of-the-art encodings of multi-maps in Java, Scala and Clojure. We
isolate key differences using microbenchmarks and validate the resulting
conclusions on a real world case in static analysis. The new encoding brings
the per key-value storage overhead down to 30B: a 2x improvement. With
additional inlining of primitive values it reaches a 4x improvement
Clear Visual Separation of Temporal Event Sequences
Extracting and visualizing informative insights from temporal event sequences
becomes increasingly difficult when data volume and variety increase. Besides
dealing with high event type cardinality and many distinct sequences, it can be
difficult to tell whether it is appropriate to combine multiple events into one
or utilize additional information about event attributes. Existing approaches
often make use of frequent sequential patterns extracted from the dataset,
however, these patterns are limited in terms of interpretability and utility.
In addition, it is difficult to assess the role of absolute and relative time
when using pattern mining techniques.
In this paper, we present methods that addresses these challenges by
automatically learning composite events which enables better aggregation of
multiple event sequences. By leveraging event sequence outcomes, we present
appropriate linked visualizations that allow domain experts to identify
critical flows, to assess validity and to understand the role of time.
Furthermore, we explore information gain and visual complexity metrics to
identify the most relevant visual patterns. We compare composite event learning
with two approaches for extracting event patterns using real world company
event data from an ongoing project with the Danish Business Authority.Comment: In Proceedings of the 3rd IEEE Symposium on Visualization in Data
Science (VDS), 201
Tooth characters of protohippine horses with special reference to species from the Merychippus zone, California
The critical review of equine tooth characters attempted in this paper is the result of a study of the protohippine horses obtained from the Merychippus Zone of the north Coalinga district, California. During the conduct of extensive excavations in this zone since 1928 by the California Institute, more than two thousand teeth of the genus Merychippus have been collected. In addition to the types represented by the equine material, a number of associated land mammals have been secured. The faunal list, which includes some fifteen species, suggests that this locality occupies a stratigraphic position approximately late middle Miocene in age.
The variation displayed in the dental characters of the merychippine material from the Merychippus Zone necessitated comparisons with cheek-teeth of Equidae from practically all of the Miocene formations furnishing vertebrate remains in the Pacific Coast and Great Basin Provinces. A comprehensive study of these collections clearly demonstrates that many of the cheek-tooth characters employed in the description of type specimens of fossil horses are variable to an extent which renders them unreliable in a determination of species. The variation of these characters within a large collection also indicates that it is possible for teeth referable to a particular species to have a wider stratigraphic range than has been hitherto appreciated. The conclusion is reached that the presence of a species has less value in reaching an age determination of the strata in which it occurs than evidence furnished by an association of several species
Depth Fields: Extending Light Field Techniques to Time-of-Flight Imaging
A variety of techniques such as light field, structured illumination, and
time-of-flight (TOF) are commonly used for depth acquisition in consumer
imaging, robotics and many other applications. Unfortunately, each technique
suffers from its individual limitations preventing robust depth sensing. In
this paper, we explore the strengths and weaknesses of combining light field
and time-of-flight imaging, particularly the feasibility of an on-chip
implementation as a single hybrid depth sensor. We refer to this combination as
depth field imaging. Depth fields combine light field advantages such as
synthetic aperture refocusing with TOF imaging advantages such as high depth
resolution and coded signal processing to resolve multipath interference. We
show applications including synthesizing virtual apertures for TOF imaging,
improved depth mapping through partial and scattering occluders, and single
frequency TOF phase unwrapping. Utilizing space, angle, and temporal coding,
depth fields can improve depth sensing in the wild and generate new insights
into the dimensions of light's plenoptic function.Comment: 9 pages, 8 figures, Accepted to 3DV 201
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