Measuring the Generalized Friendship Paradox in Networks with Quality-dependent Connectivity

The friendship paradox is a sociological phenomenon stating that most people have fewer friends than their friends do. The generalized friendship paradox refers to the same observation for attributes other than degree, and it has been observed in Twitter and scientific collaboration networks. This paper takes an analytical approach to model this phenomenon. We consider a preferential attachment-like network growth mechanism governed by both node degrees and `qualities'. We introduce measures to quantify paradoxes, and contrast the results obtained in our model to those obtained for an uncorrelated network, where the degrees and qualities of adjacent nodes are uncorrelated. We shed light on the effect of the distribution of node qualities on the friendship paradox. We consider both the mean and the median to measure paradoxes, and compare the results obtained by using these two statistics

Bayesian Surprise in Indoor Environments

This paper proposes a novel method to identify unexpected structures in 2D floor plans using the concept of Bayesian Surprise. Taking into account that a person's expectation is an important aspect of the perception of space, we exploit the theory of Bayesian Surprise to robustly model expectation and thus surprise in the context of building structures. We use Isovist Analysis, which is a popular space syntax technique, to turn qualitative object attributes into quantitative environmental information. Since isovists are location-specific patterns of visibility, a sequence of isovists describes the spatial perception during a movement along multiple points in space. We then use Bayesian Surprise in a feature space consisting of these isovist readings. To demonstrate the suitability of our approach, we take "snapshots" of an agent's local environment to provide a short list of images that characterize a traversed trajectory through a 2D indoor environment. Those fingerprints represent surprising regions of a tour, characterize the traversed map and enable indoor LBS to focus more on important regions. Given this idea, we propose to use "surprise" as a new dimension of context in indoor location-based services (LBS). Agents of LBS, such as mobile robots or non-player characters in computer games, may use the context surprise to focus more on important regions of a map for a better use or understanding of the floor plan.Comment: 10 pages, 16 figure

Efficient Immunization Strategies for Computer Networks and Populations

We present an effective immunization strategy for computer networks and populations with broad and, in particular, scale-free degree distributions. The proposed strategy, acquaintance immunization, calls for the immunization of random acquaintances of random nodes (individuals). The strategy requires no knowledge of the node degrees or any other global knowledge, as do targeted immunization strategies. We study analytically the critical threshold for complete immunization. We also study the strategy with respect to the susceptible-infected-removed epidemiological model. We show that the immunization threshold is dramatically reduced with the suggested strategy, for all studied cases.Comment: Revtex, 5 pages, 4 ps fig

Nuclear quantum optics with x-ray laser pulses

The direct interaction of nuclei with super-intense laser fields is studied. We show that present and upcoming high-frequency laser facilities, especially together with a moderate acceleration of the target nuclei, do allow for resonant laser-nucleus interaction. These direct interactions may be utilized for the optical measurement of nuclear properties such as the transition frequency and the dipole moment, thus opening the field of nuclear quantum optics. As ultimate goal, one may hope that direct laser-nucleus interactions could become a versatile tool to enhance preparation, control and detection in nuclear physics.Comment: 5 pages, 3 eps figures, revised versio

Dilepton anisotropy from p+Bep + Be and Ca+CaCa + Ca collisions at BEVALAC energies

A full calculation of lepton-pair angular characteristics is carried out for $e^+e^-$ pairs created in $p + Be$ and $Ca + Ca$ collisions from 1.0 to 2.1 GeV/A. It is demonstrated that the dilepton decay anisotropy depends sensitively on the different sources and may be used for their disentangling. Due to the dominance of the $\eta$-and $\Delta$-Dalitz decays and only a small anisotropy coefficient for $\pi^+\pi^-$ annihilation, the expected anisotropy coefficients show a decrease with invariant mass of the dilepton pair and change only moderately when comparing $p + Be$ and $Ca + Ca$ reactions at the same bombarding energy.Comment: 10 pages, LaTeX, plus 4 postscript figures tarred, compressed and uuencoded in separate fil

Experimental Studies Towards a DC-DC Conversion Powering Scheme for the CMS Silicon Strip Tracker at SLHC

The upgrade of the CMS silicon tracker for the Super-LHC presents many challenges. The distribution of power to the tracker is considered particularly difficult, as the tracker power consumption is expected to be similar to or higher than today, while the operating voltage will decrease and power cables cannot be exchanged or added. The CMS tracker has adopted parallel powering with DC-DC conversion as the baseline solution to the powering problem. In this paper, experimental studies of such a DC-DC conversion powering scheme are presented, including system test measurements with custom DC-DC converters and current strip tracker structures, studies of the detector susceptibility to conductive noise, and simulations of the effect of novel powering schemes on the strip tracker material budget

An inclusive search for supersymmetry in 13 TeV proton-proton collision data

The second run of $pp$ collisions at the Large Hadron Collider (LHC) at CERN marks one of the most anticipated eras in the field of particle physics. Already the largest and most powerful science experiment of its kind, the LHC has outdone itself, running at a record center of mass energy of $\sqrt{s}=13$ TeV and colliding protons at rates of over 600 million collisions per second. The incredible performance of the machine allows for unprecedented exploration of the TeV scale. No elementary particles have ever been observed at these energies, yet many are hypothesized as extensions to the standard model (SM), the most complete and widely accepted model of elementary particles and their interactions. Among the most sought-after hypothetical particles are those proposed by the theory of supersymmetry (SUSY). In this thesis, results are presented from a generic search for strongly producedsupersymmetric particles in $pp$ collisions in the multijet + missingtransverse momentum final state. The largest analyzed data sample corresponds to 35.9fb$^{-1}$ recorded by the CMS experiment at $\sqrt{s}=13$ TeV in 2016. This searchis motivated by SUSY models that avoidfine-tuning of the Higgs mass. In such models, strongly produced SUSY particles,including the gluino and top squark, are predicted to have masses onthe order of a TeV. These particles also have some of the highestproduction cross sections in SUSY and give rise to final states withdistinct, high jet multiplicity event signatures. To make the analysissensitive to a wide range of such final states, events are classifiedby the number of jets, the scalar sum of the transverse momenta of thejets, the vector sum of the transverse momenta of the jets, and thenumber of b-tagged jets. All SM backgrounds are measured using dedicated control samples in data. No significantexcess is observed beyond the measured SM expectation. The results areinterpreted as limits on simplified SUSY models. In these models,gluinos with masses as high as 1970 GeV and squarks with masses as high as 1450 GeV are excluded at 95\% CL forscenarios with low $\tilde{\chi}_{1}^{0}$ mass, far exceeding the limitsset in Run I

How to Conduct Store Observations of Tobacco Marketing and Products

As tobacco companies continue to heavily market their products at the point of sale, tobacco control groups seek strategies to combat the negative effects of this marketing. Store observations, which have been widely used by researchers and practitioners alike, are an excellent surveillance tool. This article provides a guide for public health practitioners interested in working in the tobacco retail environment by detailing the steps involved in conducting store observations of tobacco marketing and products including 1) obtaining tobacco product retailer lists, 2) creating measures, 3) selecting a mode of data collection, 4) training data collectors, and 5) analyzing data. We also highlight issues that may arise while in the field and provide information on disseminating results of store observations, including the potential policy implications

Validation of Kalman Filter alignment algorithm with cosmic-ray data using a CMS silicon strip tracker endcap

A Kalman Filter alignment algorithm has been applied to cosmic-ray data. We discuss the alignment algorithm and an experiment-independent implementation including outlier rejection and treatment of weakly determined parameters. Using this implementation, the algorithm has been applied to data recorded with one CMS silicon tracker endcap. Results are compared to both photogrammetry measurements and data obtained from a dedicated hardware alignment system, and good agreement is observed.Comment: 11 pages, 8 figures. CMS NOTE-2010/00