420 research outputs found
Relations between the Gribov-horizon and center-vortex confinement scenarios
We review numerical evidence on connections between the center-vortex and
Gribov-horizon confinement scenarios.Comment: Plenary talk presented by S. Olejnik at "Quark Confinement and the
Hadron Spectrum VI", Villasimius, Sardinia, Italy, Sep. 21-25, 2004; 10
pages, 11 EPS figures, uses AIP Proceedings style file
On the Unicity of Smartphone Applications
Prior works have shown that the list of apps installed by a user reveal a lot
about user interests and behavior. These works rely on the semantics of the
installed apps and show that various user traits could be learnt automatically
using off-the-shelf machine-learning techniques. In this work, we focus on the
re-identifiability issue and thoroughly study the unicity of smartphone apps on
a dataset containing 54,893 Android users collected over a period of 7 months.
Our study finds that any 4 apps installed by a user are enough (more than 95%
times) for the re-identification of the user in our dataset. As the complete
list of installed apps is unique for 99% of the users in our dataset, it can be
easily used to track/profile the users by a service such as Twitter that has
access to the whole list of installed apps of users. As our analyzed dataset is
small as compared to the total population of Android users, we also study how
unicity would vary with larger datasets. This work emphasizes the need of
better privacy guards against collection, use and release of the list of
installed apps.Comment: 10 pages, 9 Figures, Appeared at ACM CCS Workshop on Privacy in
Electronic Society (WPES) 201
Laser-induced Precession of Magnetization in GaMnAs
We report on the photo-induced precession of the ferromagnetically coupled Mn
spins in (Ga,Mn)As, which is observed even with no external magnetic field
applied. We concentrate on various experimental aspects of the time-resolved
magneto-optical Kerr effect (TR-MOKE) technique that can be used to clarify the
origin of the detected signals. We show that the measured data typically
consist of several different contributions, among which only the oscillatory
signal is directly connected with the ferromagnetic order in the sample.Comment: 4 pages, 5 figure
Polarization control of metal-enhanced fluorescence in hybrid assemblies of photosynthetic complexes and gold nanorods
Fluorescence imaging of hybrid nanostructures composed of a bacterial light-harvesting complex LH2 and Au nanorods with controlled coupling strength is employed to study the spectral dependence of the plasmon-induced fluorescence enhancement. Perfect matching of the plasmon resonances in the nanorods with the absorption bands of the LH2 complexes facilitates a direct comparison of the enhancement factors for longitudinal and transverse plasmon frequencies of the nanorods. We find that the fluorescence enhancement due to excitation of longitudinal resonance can be up to five-fold stronger than for the transverse one. We attribute this result, which is important for designing plasmonic functional systems, to a very different distribution of the enhancement of the electric field due to the excitation of the two characteristic plasmon modes in nanorods
Evidence for Excimer Photoexcitations in an Ordered {\pi}-Conjugated Polymer Film
We report pressure-dependent transient picosecond and continuous-wave
photomodulation studies of disordered and ordered films of
2-methoxy-5-(2-ethylhexyloxy) poly(para-phenylenevinylene). Photoinduced
absorption (PA) bands in the disordered film exhibit very weak pressure
dependence and are assigned to intrachain excitons and polarons. In contrast,
the ordered film exhibits two additional transient PA bands in the midinfrared
that blueshift dramatically with pressure. Based on high-order configuration
interaction calculations we ascribe the PA bands in the ordered film to
excimers. Our work brings insight to the exciton binding energy in ordered
films versus disordered films and solutions. The reduced exciton binding energy
in ordered films is due to new energy states appearing below the continuum band
threshold of the single strand.Comment: 5.5 pages, 5 figure
Material microstructure effects in micro-endmilling of Cu99.9E
This article presents an investigation of the machining response of metallurgically and mechanically modified materials at the micro-scale. Tests were conducted that involved micro-milling slots in coarse-grained Cu99.9E with an average grain size of 30â”m and ultrafine-grained Cu99.9E with an average grain size of 200ânm, produced by equal channel angular pressing. A new method based on atomic force microscope measurements is proposed for assessing the effects of material homogeneity changes on the minimum chip thickness required for a robust micro-cutting process with a minimum surface roughness. The investigation has shown that by refining the material microstructure the minimum chip thickness can be reduced and a high surface finish can be obtained. Also, it was concluded that material homogeneity improvements lead to a reduction in surface roughness and surface defects in micro-cutting
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