ADJUSTABLE PHASE-CONTROL IN STABILIZED INTERFEROMETRY

We report an optoelectronic feedback loop that permits the active stabilization of an interferometric setup for any chosen Value of the phase between the interfering beams. This method is based on phase modulation and homodyne detection techniques. The phase can be stabilized with a precision of better than 1 deg for our experimental conditions.20663563

Handling oversampling in dynamic networks using link prediction

Oversampling is a common characteristic of data representing dynamic networks. It introduces noise into representations of dynamic networks, but there has been little work so far to compensate for it. Oversampling can affect the quality of many important algorithmic problems on dynamic networks, including link prediction. Link prediction seeks to predict edges that will be added to the network given previous snapshots. We show that not only does oversampling affect the quality of link prediction, but that we can use link prediction to recover from the effects of oversampling. We also introduce a novel generative model of noise in dynamic networks that represents oversampling. We demonstrate the results of our approach on both synthetic and real-world data.Comment: ECML/PKDD 201

Effect of different enrichment media and DNA extraction techniques on Salmonella detection by PCR in SWINE feces

The aim of this study was to evaluate different selective enrichment broths and DNA extraction techniques on the detection of Salmonella Typhimurium in swine feces by PCR. Feces samples (n=10) were inoculated with approximately 102 Salmonella Typhimurium organisms, first enriched in GN-Hajna broth and secondly enriched in Rappaport-Vassiliadis, Muller-Kaufmann tetrathionate and selenite-cystine broths. In order to produce DNA-templates for PCR, aliquots from the broths were subjected to three DNA extraction methods: boiling-centrifugation, salting-out and phenol-chloroform. Detection of Salmonella was significant lower when phenol-chloroform was applied to selenite-cystine and Muller-Kaufmann tetrathionate (P\u3c0.05). The boiling-centrifugation technique had best cost/benefit ratio and can be successfully used as a rapid DNA template preparation from the three enriched broths tested

Efficient LZ78 factorization of grammar compressed text

We present an efficient algorithm for computing the LZ78 factorization of a text, where the text is represented as a straight line program (SLP), which is a context free grammar in the Chomsky normal form that generates a single string. Given an SLP of size $n$ representing a text $S$ of length $N$, our algorithm computes the LZ78 factorization of $T$ in $O(n\sqrt{N}+m\log N)$ time and $O(n\sqrt{N}+m)$ space, where $m$ is the number of resulting LZ78 factors. We also show how to improve the algorithm so that the $n\sqrt{N}$ term in the time and space complexities becomes either $nL$, where $L$ is the length of the longest LZ78 factor, or $(N - \alpha)$ where $\alpha \geq 0$ is a quantity which depends on the amount of redundancy that the SLP captures with respect to substrings of $S$ of a certain length. Since $m = O(N/\log_\sigma N)$ where $\sigma$ is the alphabet size, the latter is asymptotically at least as fast as a linear time algorithm which runs on the uncompressed string when $\sigma$ is constant, and can be more efficient when the text is compressible, i.e. when $m$ and $n$ are small.Comment: SPIRE 201

Analysis of ball milling time to produce self-lubricating copper-tungsten disulfide composite: best trade-off between tribological performance and electrical properties

Ball milling is a fundamental step of powder metallurgy widely employed for composite manufacturing. This work focuses on the influence of ball milling time on the morphological, electrical, and tribological properties of self-lubricating copper-tungsten disulfide (Cu-WS2) composites. The study investigates ball milling times between 1 and 24 h to guarantee different degrees of incorporation of WS2 in the copper matrix. Micro-scratch and wear tests are performed to evaluate the tribological behavior. Optical, scanning electron, and confocal laser scanning microscopy analyze the scratch and wear tracks. The results show the reliability of the production process and a general improvement of the composites’ mechanical properties compared to pure copper. The addition of WS2 enhances the tribo-mechanical properties, increasing hardness and wear resistance and decreasing the friction coefficient. Shorter ball milling times result in larger WS2 flakes distributed in the copper matrix, while longer ball milling times result in smaller and more dispersed particles. This homogeneous fine dispersion determines a difference in the composites’ electrical conductivity and tribological performance, with shorter ball milling times (i.e., between 2 and 4 h) offering the best trade-off between wear behavior and electrical properties

Stool processing-methods for Salmonella enterica isolation and PCR detection

The aim of this study was to compare the efficiency of three protocols for bacteriological isolation of Salmonella enterica and detection by PCR in swine feces samples. Pool of feces (n=62) were processed by three different methods. Method 1: samples (10g) were pre-enriched in BPW (1:10) and enriched in Rappaport-Vassiliadis broth (1:100). Method 2: samples (1g) were first enriched in GN-Hajna broth (1:10) and secondly enriched in Muller-Kaufmann tetrathionate broth (1`:10). Method 3: Single step enrichment of feces (1g) in selenite-cystine broth (1:10). PCR was performed using DNA extracted from the last enrichment broth of each bacteriological method. Salmonella enterica was cultured from 13 out of 62 samples (20.9%) and seven different serotypes were isolated. The methods 1, 2 and 3 resulted in 9 (14.5%), 6 (9.6%) and 2 (3.2%) positive samples, respectively. PCR was significantly superior than conventional bacteriology for Salmonella detection only when Rappaport-Vassiliadis was used for DNA-template preparation