Efficient Estimation of Mutual Information for Strongly Dependent Variables

We demonstrate that a popular class of nonparametric mutual information (MI) estimators based on k-nearest-neighbor graphs requires number of samples that scales exponentially with the true MI. Consequently, accurate estimation of MI between two strongly dependent variables is possible only for prohibitively large sample size. This important yet overlooked shortcoming of the existing estimators is due to their implicit reliance on local uniformity of the underlying joint distribution. We introduce a new estimator that is robust to local non-uniformity, works well with limited data, and is able to capture relationship strengths over many orders of magnitude. We demonstrate the superior performance of the proposed estimator on both synthetic and real-world data.Comment: 13 pages, to appear in International Conference on Artificial Intelligence and Statistics (AISTATS) 201

Concentrated suspensions of Brownian beads in water: dynamic heterogeneities trough a simple experimental technique

Concentrated suspensions of Brownian hard-spheres in water are an epitome for understanding the glassy dynamics of both soft materials and supercooled molecular liquids. From an experimental point of view, such systems are especially suited to perform particle tracking easily, and, therefore, are a benchmark for novel optical techniques, applicable when primary particles cannot be resolved. Differential Variance Analysis (DVA) is one such novel technique that simplifies significantly the characterization of structural relaxation processes of soft glassy materials, since it is directly applicable to digital image sequences of the sample. DVA succeeds in monitoring not only the average dynamics, but also its spatio-temporal fluctuations, known as dynamic heterogeneities. In this work, we study the dynamics of dense suspensions of Brownian beads in water, imaged through digital video-microscopy, by using both DVA and single-particle tracking. We focus on two commonly used signatures of dynamic heterogeneities: the dynamic susceptibility, $\chi_4$, and the non-Gaussian parameter, $\alpha_2$. By direct comparison of these two quantities, we are able to highlight similarities and differences. We do confirm that $\chi_4$ and $\alpha_2$ provide qualitatively similar information, but we find quantitative discrepancies in the scalings of characteristic time and length scale on approaching the glass transition.Comment: The original publication is available at http://www.scichina.com and http://www.springerlink.com http://engine.scichina.com/publisher/scp/journal/SCPMA/doi/10.1007/s11433-019-9401-x?slug=abstrac

Special Libraries, December 1975

Volume 66, Issue 12https://scholarworks.sjsu.edu/sla_sl_1975/1009/thumbnail.jp

New Silver Nanosensor for Nickel Traces. Part II: Urinary Nickel Determination Associated to Smoking Addiction

A new fluorescence silver nanosensor assisted by surfactant has been recently synthesized and applied to ultra trace nickel determination. The methodology was validated by the standard addition method and satisfactorily applied to nickel determination in urine without previous treatment, coming from subjects with different smoking addiction levels and second hand smokers. Within-day precision was better than 0.011 CV. The reproducibility (between-days precision) was also evaluated over 3 days by performing six determinations each day with a CV of 0.025. The proposed methodology represents a promising approach in the area of biological monitoring due to its low operation cost, simplicity of instrumentation, high sampling speed and non-polluting solvents. Obtained results of urinary nickel concentration were successfully correlated with the tobacco addiction.Fil: Talio, María Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; ArgentinaFil: Luconi, M. O.. Universidad Nacional de San Luis; ArgentinaFil: Fernandez, Liliana Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Química de San Luis. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia. Instituto de Química de San Luis; Argentin

Evolution of Conversations in the Age of Email Overload

Email is a ubiquitous communications tool in the workplace and plays an important role in social interactions. Previous studies of email were largely based on surveys and limited to relatively small populations of email users within organizations. In this paper, we report results of a large-scale study of more than 2 million users exchanging 16 billion emails over several months. We quantitatively characterize the replying behavior in conversations within pairs of users. In particular, we study the time it takes the user to reply to a received message and the length of the reply sent. We consider a variety of factors that affect the reply time and length, such as the stage of the conversation, user demographics, and use of portable devices. In addition, we study how increasing load affects emailing behavior. We find that as users receive more email messages in a day, they reply to a smaller fraction of them, using shorter replies. However, their responsiveness remains intact, and they may even reply to emails faster. Finally, we predict the time to reply, length of reply, and whether the reply ends a conversation. We demonstrate considerable improvement over the baseline in all three prediction tasks, showing the significant role that the factors that we uncover play, in determining replying behavior. We rank these factors based on their predictive power. Our findings have important implications for understanding human behavior and designing better email management applications for tasks like ranking unread emails.Comment: 11 page, 24th International World Wide Web Conferenc

Applications of physical methods in high-frequency futures markets

In the present work we demonstrate the application of different physical methods to high-frequency or tick-by-tick financial time series data. In particular, we calculate the Hurst exponent and inverse statistics for the price time series taken from a range of futures indices. Additionally, we show that in a limit order book the relaxation times of an imbalanced book state with more demand or supply can be described by stretched exponential laws analogous to those seen in many physical systems.Comment: 14 Pages and 10 figures. Proceeding to the SPIE conference, 4 - 7 December 2007 Australian National Univ. Canberra, ACT, Australi

Science on television : how? Like that!

This study explores the presence of science programs on the Flemish public broadcaster between 1997 and 2002 in terms of length, science domains, target groups, production mode, and type of broadcast. Our data show that for nearly all variables 2000 can be marked as a year in which the downward spiral for science on television was reversed. These results serve as a case study to discuss the influence of public policy and other possible motives for changes in science programming, as to gain a clearer insight into the factors that influence whether and how science programs are broadcast on television. Three factors were found to be crucial in this respect: 1) public service philosophy, 2) a strong governmental science policy providing structural government support, and 3) the reflection of a social discourse that articulates a need for more hard sciences