Search for ttˉt\bar{t} resonances in semileptonic final states in pp collisions at s\sqrt{s} = 8 TeV

A search for the production of new heavy resonances produced in proton-proton collisions at the CMS Experiment that decay into top quark pairs is presented. Data was recorded at a center of mass energy of 8 TeV and corresponds to an integrated luminosity of 19.6 fb$^{-1}$. Results are presented as a combination of two dedicated searches, the first optimized for kinematic threshold production of top quark pairs and the second optimized for a highly boosted regime. No excess is observed above the expected yield from SM processes. In the absence of any excess we set the following limits at 95% CL on the production of non-SM particles. Top color Z' bosons with relative widths of 1.2% and 10% are excluded for masses below 2.10 TeV and 2.68 TeV. Upper limits of 1.94 pb and 0.029 pb are set on the production cross section times branching fraction for narrow resonances with masses of 0.5 TeV and 2 TeV. Likewise, limits of 1.71 pb and 0.045 pb are set for wide resonances with masses of 0.5 TeV and 2 TeV. In addition, Kaluza-Klein excitations of a gluon with masses below 2.54 TeV in the Randall-Sundrum model are excluded and an upper limit of 0.101 pb is set for a resonance mass of 2 TeV.Comment: Presentation at the DPF 2013 Meeting of the American Physical Society Division of Particles and Fields, Santa Cruz, California, August 13-17, 201

Automatically Annotating the MIR Flickr Dataset: Experimental Protocols, Openly Available Data and Semantic Spaces

The availability of a large, freely redistributable set of high-quality annotated images is critical to allowing researchers in the area of automatic annotation, generic object recognition and concept detection to compare results. The recent introduction of the MIR Flickr dataset allows researchers such access. A dataset by itself is not enough, and a set of repeatable guidelines for performing evaluations that are comparable is required. In many cases it also is useful to compare the machine-learning components of different automatic annotation techniques using a common set of image features. This paper seeks to provide a solid, repeatable methodology and protocol for performing evaluations of automatic annotation software using the MIR Flickr dataset together with freely available tools for measuring performance in a controlled manner. This protocol is demonstrated through a set of experiments using a “semantic space” auto-annotator previously developed by the authors, in combination with a set of visual term features for the images that has been made publicly available for download. The paper also discusses how much training data is required to train the semantic space annotator with the MIR Flickr dataset. It is the hope of the authors that researchers will adopt this methodology and produce results from their own annotators that can be directly compared to those presented in this work

Semantic Retrieval and Automatic Annotation: Linear Transformations, Correlation and Semantic Spaces

This paper proposes a new technique for auto-annotation and semantic retrieval based upon the idea of linearly mapping an image feature space to a keyword space. The new technique is compared to several related techniques, and a number of salient points about each of the techniques are discussed and contrasted. The paper also discusses how these techniques might actually scale to a real-world retrieval problem, and demonstrates this though a case study of a semantic retrieval technique being used on a real-world data-set (with a mix of annotated and unannotated images) from a picture library

Labour Market Reform and the Evolution of the Racial Wage Hierarchy in Post-Apartheid South Africa

The central theme of this working paper is the way that the racial wage hierarchy evolved in South Africa over the period 1993 to 1999 amongst full-time regular employees of normal working age, but excluding those in the primary sector and the defence forces

An accelerometer based-feedback technique for improving dynamic performance of a machine tool

A novel concept for improving machine dynamic performance was developed and realised, a virtual metrology frame, for a small size CNC machine with flexible frame. Its implementation in a simplified linear motion system shows a reduction in the magnitude of the first resonance in the plant frequency response function by 12 dB. Realising the concept required developing a real -time accelerometer-based measurement technique. It shows a low sensor noise σ=30 nm with optimal phase delay of <70 μs

Optimized estimator for real-time dynamic displacement measurement using accelerometers

This paper presents a method for optimizing the performance of a real-time, long term, and accurate accelerometer based displacement measurement technique, with no physical reference point. The technique was applied in a system for measuring machine frame displacement. The optimizer has three objectives with the aim to minimize phase delay, gain error and sensor noise. A multi-objective genetic algorithm was used to find Pareto optimal estimator parameters. The estimator is a combination of a high pass filter and a double integrator. In order to reduce the gain and phase errors two approaches have been used: zero placement and pole-zero placement. These approaches were analysed based on noise measurement at 0g-motion and compared. Only the pole-zero placement approach met the requirements for phase delay, gain error, and sensor noise. Two validation experiments were carried out with a Pareto optimal estimator. First, long term measurements at 0g-motion with the experimental setup were carried out, which showed displacement error of 27.6 ± 2.3 nm. Second, comparisons between the estimated and laser interferometer displacement measurements of the vibrating frame were conducted. The results showed a discrepancy lower than 2 dB at the required bandwidth

Summation of rational series twisted by strongly B-multiplicative coefficients

We evaluate in closed form series of the type $\sum u(n) R(n)$, where $(u(n))_n$ is a strongly $B$-multiplicative sequence and $R(n)$ a (well-chosen) rational function. A typical example is: $$\sum_{n \geq 1} (-1)^{s_2(n)} \frac{4n+1}{2n(2n+1)(2n+2)} = -\frac{1}{4}$$ where $s_2(n)$ is the sum of the binary digits of the integer $n$. Furthermore closed formulas for series involving automatic sequences that are not strongly $B$-multiplicative, such as the regular paperfolding and Golay-Shapiro-Rudin sequences, are obtained; for example, for integer $d \geq 0$: $$\sum_{n \geq 0} \frac{v(n)}{(n+1)^{2d+1}} = \frac{\pi^{2d+1} |E_{2d}|}{(2^{2d+2}-2)(2d)!}$$ where $(v(n))_n$ is the $\pm 1$ regular paperfolding sequence and $E_{2d}$ is an Euler number.Comment: Typo in a crossreference corrected in Example 9, page 6. Remark added top of Page 9 about the relation between paperfolding and the Jacobi-Kronecker symbo