Effects of depolarizing quantum channels on BB84 and SARG04 quantum cryptography protocols

We report experimental studies on the effect of the depolarizing quantum channel on weak-pulse BB84 and SARG04 quantum cryptography. The experimental results show that, in real world conditions in which channel depolarization cannot be ignored, BB84 should perform better than SARG04.Comment: 4 pages, 4 figure

Study of the Top-quark Pair Production in Association with a Bottom-quark Pair from Fast Simulations at the LHC

A large number of top quarks will be produced at the Large Hadron Collider (LHC) for Run II period. This will allow us to measure the rare processes from the top sector in great details. We present the study of the top-quark pair production in association with a bottom-quark pair (ttbb) from fast simulations for the Compact Muon Solenoid (CMS) experiment. The differential distributions of ttbb are compared with the top-quark pair production with two additional jets (ttjj) and with the production in association with the Higgs (ttH), where the Higgs decays to a bottom-quark pair. The significances of ttbb process in the dileptonic and semileptonic decay mode are calculated with the data corresponding to an integrated luminosity of 10 fb-1, which is foreseen to be collected in the early Run II period. This study will be an important input in searching for new physics beyond the standard model as well as in searching for ttH process where the Yukawa coupling with the top quark can be directly measured.Comment: 12 pages, 12 figure

Comment on ``Solution of Classical Stochastic One-Dimensional Many-Body Systems''

In a recent Letter, Bares and Mobilia proposed the method to find solutions of the stochastic evolution operator $H=H_0 + {\gamma\over L} H_1$ with a non-trivial quartic term $H_1$. They claim, ``Because of the conservation of probability, an analog of the Wick theorem applies and all multipoint correlation functions can be computed.'' Using the Wick theorem, they expressed the density correlation functions as solutions of a closed set of integro-differential equations. In this Comment, however, we show that applicability of Wick theorem is restricted to the case $\gamma = 0$ only.Comment: 1 page, revtex style, comment on paper Phys. Rev. Lett. {\bf 83}, 5214 (1999

A Study of Personal and Environmental Factors Influencing Bullying

This study aims to find out the differences in the bullying experience between boys and girls in different perspectives and to find out the predictive power of cognitive, social and environmental factors on students’ bully and victim tendencies. At last, through this research, this study aims to gain a synthetic perspective on bully phenomenon by considering various aspects in order to provide a theoretical and empirical reference for preventing and intervening bullying problem. The sample size of students used in the analysis was 405 (271 boys and 134 girls) between 12 and 14 years. They were in seventh and eighth grade at two middle schools in Mokpo Korea. 306 caregivers of the students participated in the survey. As the results of this study, there was no difference in perpetrating bullying or being bullied between boys and girls. Most students and bullies attribute the reason of bullying to the victims’ eye-catching characteristics or social skill problems. On the other hand, most victims did not know reason of bullying. Social support, self-concept, attributional style, and cultural beliefs could predict bully tendency and victim tendency. Above all, the most important factor, that relates to bully and victim tendency, is perceived social supports, especially parental supports. Parents concerning about their child can be most strongest prevention of students bullying problems

Microspinning: Local Surface Mixing via Rotation of Magnetic Microparticles for Efficient Small-Volume Bioassays

The need for high-throughput screening has led to the miniaturization of the reaction volume of the chamber in bioassays. As the reactor gets smaller, surface tension dominates the gravitational or inertial force, and mixing efficiency decreases in small-scale reactions. Because passive mixing by simple diffusion in tens of microliter-scale volumes takes a long time, active mixing is needed. Here, we report an efficient micromixing method using magnetically rotating microparticles with patterned magnetization induced by magnetic nanoparticle chains. Because the microparticles have magnetization patterning due to fabrication with magnetic nanoparticle chains, the microparticles can rotate along the external rotating magnetic field, causing micromixing. We validated the reaction efficiency by comparing this micromixing method with other mixing methods such as simple diffusion and the use of a rocking shaker at various working volumes. This method has the potential to be widely utilized in suspension assay technology as an efficient mixing strategy