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Events for March

  • W.V.T. Rusch Engineering Honors Program Colloquium

    Fri, Mar 03, 2017 @ 01:00 PM - 01:50 PM

    USC Viterbi School of Engineering

    University Calendar


    Join us for a presentation by Prof. Paul Rothemund, Dept. of Bioengineering at California Institute of Technology, titled "DNA Origami: Folded DNA as a Building Material for Molecular Devices."

    Location: Henry Salvatori Computer Science Center (SAL) - 101

    Audiences: Everyone Is Invited

    Posted By: Ramon Borunda/Academic Services

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  • PhD Defense - Lian Liu

    Thu, Mar 09, 2017 @ 02:00 PM - 04:00 PM

    Computer Science

    University Calendar


    PhD Candidate: Lian Liu

    Committee: Ming-Deh Huang (CS, chair), Sheldon Ross (ISE), Shang-Hua Teng (CS)

    Title: Expander Cayley Graphs over Finite Strings and Pseudorandomness

    Time: March 9 (Thursday) 2:00 - 3:30 pm.

    Room: SAL 322 (i.e. the conference room on the 3rd floor of SAL)


    Abstract:

    We present an explicit construction of expander Cayley graphs over the direct sum of multiple copies of Z/pZ, where p is a prime number. So far as we know, our work is the first expander Cayley graph construction over such groups. Our construction consists of two phases. In the first phase, we consider Cayley graphs over the multiplicative groups of algebras over finite fields. We prove that for some well-chosen small generating sets which can be computed in polynomial time, the induced Cayley graphs are expanding. In the second phase, we construct an new Cayley graph by projecting the graph created in the first phase onto a direct component of the underlying group. We showed that the component on which the graph is projected is isomorphic to the direct sum of multiple copies of Z/pZ, and the resulting Cayley graph is a good expander. Interestingly, we found that many expander graphs whose degrees are not of any special forms can be explicitly constructed under this framework, which could be regarded as a tiny progress towards the open problem of constructing infinite families of Ramanujan graphs of every degree.

    An special case of particular interest is when p equals 2. In this situation, the vertices of such a graph naturally correspond to bit strings of a fixed length, and each edge represents a transition between two bit strings under standard exclusive-or operation. As an application, we then propose a simple pseudorandom generator based on random walks on the graph. An important question is whether our pseudorandom generator is indistinguishable from a truly random source under probabilistic polynomial time attacks, which, however, remains open. In fact, constructing a secure and efficient pseudorandom generator has been an open problem since the birth of modern cryptography, whose solution may lead to huge breakthroughs in computer science. Therefore, our goal here is not addressing this problem, even partially. Instead, along with our discussion, we demonstrate that our expander Cayley graphs have some appealing features that all previous constructions do not have. These new features might bring a lot of potential topics for future research.

    Location: Henry Salvatori Computer Science Center (SAL) - 322

    Audiences: Everyone Is Invited

    Posted By: Lizsl De Leon

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  • W.V.T. Rusch Engineering Honors Program Colloquium

    Fri, Mar 10, 2017 @ 01:00 PM - 01:50 PM

    USC Viterbi School of Engineering

    University Calendar


    Join us for a presentation by Prof. David Prober, Division of Biology at California Institute of Technology, titled "Using Fish to Understand How and Why We Sleep."

    Location: Henry Salvatori Computer Science Center (SAL) - 101

    Audiences: Everyone Is Invited

    Posted By: Ramon Borunda/Academic Services

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  • W.V.T. Rusch Engineering Honors Program Colloquium

    Fri, Mar 24, 2017 @ 01:00 PM - 01:50 PM

    USC Viterbi School of Engineering

    University Calendar


    Join us for a presentation by Dr. Vikram Ravi, Millikan Fellow in Astronomy, Cahill Center for Astronomy and Physics at the California Institute of Technology, titled "The Hottest Explosions of the Universe."

    Location: Henry Salvatori Computer Science Center (SAL) - 101

    Audiences: Everyone Is Invited

    Posted By: Ramon Borunda/Academic Services

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  • PhD Defense - Christopher Wienberg

    Tue, Mar 28, 2017 @ 11:00 AM - 01:00 PM

    Computer Science

    University Calendar


    Title: Demographic Bias Correction for Social Media Data

    PhD Candidate: Christopher Wienberg

    Date and Time: Tuesday, March 28th, 11:00am
    Location: Zumberge Hall (ZHS) 360

    Abstract:
    For generations, people have been keeping records of their everyday lives. The web is now a popular place for people to document their personal lives, replacing journals and diaries popular decades ago. The popularity of weblogs and social media has provided an unique opportunity to study people at a massive scale. Social media researchers have seized this chance to use social media data to predict and measure social phenomena, such as elections, economic activity, and public health. While these researchers' work has shown promise, they frequently highlight a challenge with web data: web users, as a group, are dissimilar (e.g. younger, wealthier) from most offline populations.

    Demographic representativity is an issue that economists and other social scientists deal with regularly. They have found that re-weighting survey samples based on demographic variables like age and gender can improve the accuracy of survey results. They directly account for this need by asking survey respondents to provide their demographic background. In contrast, social media analysts do not have immediate access to these demographic variables.

    This dissertation proposes and evaluates a practical approach for making social predictions from social media data while contending with demographic representativity issues. It describes the collection and analysis of reliable data describing a population of web users. Social predictions are drawn from this population, with various bias correction techniques evaluated by comparing to gold standard data from traditionally collected surveys. Special attention is paid to important practical considerations, such as errors introduced by automated methods to characterize the demographic and other attributes of individual users and their impact on predictions for the broader population.

    Committee:
    Andrew S. Gordon (chair)
    Ellis Horowitz
    Arie Kapteyn

    Location: James H. Zumberge Hall Of Science (ZHS) - 360

    Audiences: Everyone Is Invited

    Posted By: Lizsl De Leon

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  • W.V.T. Rusch Engineering Honors Program Colloquium

    Fri, Mar 31, 2017 @ 01:00 PM - 01:50 PM

    USC Viterbi School of Engineering

    University Calendar


    Join us for a presentation by Prof. Neil G. Siegel, IBM Professor of Engineering Management, Daniel J. Epstein Dept. of Industrial and Systems Engineering, titled "An Engineering Career in Private Industry."

    Location: Henry Salvatori Computer Science Center (SAL) - 101

    Audiences: Everyone Is Invited

    Posted By: Ramon Borunda/Academic Services

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