3,467 research outputs found

    Randomness Extraction in AC0 and with Small Locality

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    Randomness extractors, which extract high quality (almost-uniform) random bits from biased random sources, are important objects both in theory and in practice. While there have been significant progress in obtaining near optimal constructions of randomness extractors in various settings, the computational complexity of randomness extractors is still much less studied. In particular, it is not clear whether randomness extractors with good parameters can be computed in several interesting complexity classes that are much weaker than P. In this paper we study randomness extractors in the following two models of computation: (1) constant-depth circuits (AC0), and (2) the local computation model. Previous work in these models, such as [Vio05a], [GVW15] and [BG13], only achieve constructions with weak parameters. In this work we give explicit constructions of randomness extractors with much better parameters. As an application, we use our AC0 extractors to study pseudorandom generators in AC0, and show that we can construct both cryptographic pseudorandom generators (under reasonable computational assumptions) and unconditional pseudorandom generators for space bounded computation with very good parameters. Our constructions combine several previous techniques in randomness extractors, as well as introduce new techniques to reduce or preserve the complexity of extractors, which may be of independent interest. These include (1) a general way to reduce the error of strong seeded extractors while preserving the AC0 property and small locality, and (2) a seeded randomness condenser with small locality.Comment: 62 page

    Personalized Acoustic Modeling by Weakly Supervised Multi-Task Deep Learning using Acoustic Tokens Discovered from Unlabeled Data

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    It is well known that recognizers personalized to each user are much more effective than user-independent recognizers. With the popularity of smartphones today, although it is not difficult to collect a large set of audio data for each user, it is difficult to transcribe it. However, it is now possible to automatically discover acoustic tokens from unlabeled personal data in an unsupervised way. We therefore propose a multi-task deep learning framework called a phoneme-token deep neural network (PTDNN), jointly trained from unsupervised acoustic tokens discovered from unlabeled data and very limited transcribed data for personalized acoustic modeling. We term this scenario "weakly supervised". The underlying intuition is that the high degree of similarity between the HMM states of acoustic token models and phoneme models may help them learn from each other in this multi-task learning framework. Initial experiments performed over a personalized audio data set recorded from Facebook posts demonstrated that very good improvements can be achieved in both frame accuracy and word accuracy over popularly-considered baselines such as fDLR, speaker code and lightly supervised adaptation. This approach complements existing speaker adaptation approaches and can be used jointly with such techniques to yield improved results.Comment: 5 pages, 5 figures, published in IEEE ICASSP 201

    Growth and Properties of BiMnO3 Thin Films

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    BiMnO3 thin films were epitaxially grown on SrTiO3 (100) substrates using pulsed laser deposition (PLD). The growth of thin films was extremely sensitive to substrate deposition temperatures, and single-phase BiMnO3 only could be formed in a narrow temperature window of around 640°C in an oxygen pressure of 75mTorr. It was found that the post annealing at 550°C in an oxygen pressure of 7.6×105 mTorr effectively improved the crystallinity of the film. The BiMnO3 films were found to be strongly (-202) oriented. The out-of-plane orientation relationship was (-202) BiMnO3 || (100) SrTiO3. From the result of phi (φ) scan, the (-202) plane showed a four-fold rotational symmetry, and the existence of a 45°rotation between the SrTiO3 (100) plane and the BiMnO3 (-202) plane. Magnetic measurements revealed that the BiMnO3 thin film was ferromagnetic with a Curie temperature (Tc) of about 80K, lower than that of the bulk material.Open Acces

    The Taiwanese-American Perspective on Discrimination in English Language Teaching

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    This is a qualitative study examining the perspectives of five Taiwanese-American English teachers on their experiences of discrimination in the English language-teaching field of Taiwan. An extensive amount of literature has been written about the nativeness paradigm and its effect on the English language-teaching field, but the Taiwanese-American experience concerning those issues has yet to be explored. The study used Asian Critical Race Theory, Social Identity Theory and Asian American Racial Identity Theory to analyze the history of English language teaching in Taiwan, the critical studies on native and non-native English language teachers and the social issues affecting Asian Americans in Taiwan. The study found that all of the participants were aware of the notions of hiring discrimination and stereotypes against ethnically Asian English teachers, but not all participants believed that it had a negative impact on their social identity or self-identity. This study offers a voice to Taiwanese-American English teachers in hopes of encouraging a more progressive attitude towards the diversity of all English teachers in Taiwan

    EFFECTS OF POLYUNSATURATED FATTY ACIDS ON MULTIDRUG RESISTANCE AND DNA METHYLATION IN HUMAN CANCER CELL LINES

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    Accumulating evidences indicate that dietary intake of long-chain polyunsaturated fatty acids (PUFAs) can affect various cellular processes and improve response of cancer cells to chemotherapy. The mechanisms by which PUFAs affect this response are not well understood. P-glycoprotein (P-gp), encoded by the multidrug resistance gene MDR1, is a drug efflux transporter that plays an important role in the bioavailability of anti-cancer drugs. Effects of long-chain polyunsaturated fatty acids on MDR1 gene expression and functional activity in the human colon cancer cell line Caco-2 were studied in this research. Caco-2 cells were treated with different concentrations of three PUFAs: eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA). All three PUFAs down-regulated the expression of the MDR1 gene (EPA, 34%, DHA, 32% and AA, 27%). The inhibition of gene expression by these PUFAs was accompanied by reduction in protein levels of P-gp. The calcein-AM efflux assay indicated that EPA, DHA, and AA can increase intracellular accumulation (hence decrease the efflux) of calcein-AM (a P-gp substrate) by 25% to 31%. In addition, incubation of cells with PUFAs greatly enhanced the cytotoxicity of the anti-cancer drug paclitaxel. All three PUFAs also induced apoptosis and enhanced paclitaxel-induced apoptosis in Caco-2 cells. Together, these results suggest that inhibition of the multidrug resistance MDR1/P-gp is one mechanism through which dietary polyunsaturated fatty acids exert a positive effect on the response of tumor cells to anti-cancer drugs. In addition, transcriptional promotion of the nuclear receptors CAR and PXR by PUFAs was also observed in this study. Moreover, to determine whether the eicosapentaenoic acid affects BRCA1 expression through promoter methylation, BRCA1 promoter methylation patterns and gene expression in U937 cells were examined. The methylation status of the BRCA1 promoter was evaluated by methylation-specific PCR (MSP) of bisulfite conversion products. The results indicate that methylation of BRCA1 promoter DNA is reduced in EPA-treated cells. The reduction of methylation in the BRCA1 promoter was accompanied by an increase in mRNA levels obtained by real-time quantitative PCR (qPCR), suggesting that DNA methylation is a possible mechanism by which the dietary polyunsaturated fatty acids mediate gene expression in human cells. Because of these characteristics, use of PUFAs as adjuvants presents a promising strategy in cancer prevention and therapeutics

    The New York Philharmonic Strike of 1973

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    The New York Philharmonic Strike of 1973 is a story waiting to be told. The sole volume to mention it, John Canarina\u27s The New York Philharmonic, devotes less than two pages to it. Until now, the full story has lain buried in archival documents, newspaper articles, and the memories of those who experienced it firsthand. This document represents the first comprehensive examination of this event. The research upon which it is based consists of: interviews with the New York Philharmonic members; research in the New York Philharmonic Archives; newspaper articles and reviews. The results are presented here in three interrelated narratives: a) the historical background to the tenor of labor relations between orchestral musicians and their respective managements in the United States going back more than a century, with a detailed focus upon past labor relations of the New York Philharmonic; b) a comprehensive narrative of the 1973 strike; and c) a study of the consequences of the strike for the Philharmonic with an overview of current and potentially future problems in labor relations for both the Philharmonic and rest of American symphony orchestras

    Time Quantified Monte Carlo Algorithm for Interacting Spin Array Micromagnetic Dynamics

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    In this paper, we reexamine the validity of using time quantified Monte Carlo (TQMC) method [Phys. Rev. Lett. 84, 163 (2000); Phys. Rev. Lett. 96, 067208 (2006)] in simulating the stochastic dynamics of interacting magnetic nanoparticles. The Fokker-Planck coefficients corresponding to both TQMC and Langevin dynamical equation (Landau-Lifshitz-Gilbert, LLG) are derived and compared in the presence of interparticle interactions. The time quantification factor is obtained and justified. Numerical verification is shown by using TQMC and Langevin methods in analyzing spin-wave dispersion in a linear array of magnetic nanoparticles.Comment: Accepted for publication in Phys. Rev.
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