152 research outputs found
Algorithms and Software for the Analysis of Large Complex Networks
The work presented intersects three main areas, namely graph algorithmics, network science and applied software engineering. Each computational method discussed relates to one of the main tasks of data analysis: to extract structural features from network data, such as methods for community detection; or to transform network data, such as methods to sparsify a network and reduce its size while keeping essential properties; or to realistically model networks through generative models
On predictions from spontaneously broken flavor symmetries
We discuss the predictive power of supersymmetric models with flavor
symmetries, focusing on the lepton sector of the standard model. In particular,
we comment on schemes in which, after certain `flavons' acquire their vacuum
expectation values (VEVs), the charged lepton Yukawa couplings and the neutrino
mass matrix appear to have certain residual symmetries. In most analyses, only
corrections to the holomorphic superpotential from higher-dimensional operators
are considered (for instance, in order to generate a realistic
mixing angle). In general, however, the flavon VEVs also modify the K\"ahler
potential and, therefore, the model predictions. We show that these corrections
to the naive results can be sizable. Furthermore, we present simple analytic
formulae that allow us to understand the impact of these corrections on the
predictions for the masses and mixing parameters.Comment: 12 pages, 4 figures; improved version matching PLB articl
Static and Dynamic Aspects of Scientific Collaboration Networks
Collaboration networks arise when we map the connections between scientists
which are formed through joint publications. These networks thus display the
social structure of academia, and also allow conclusions about the structure of
scientific knowledge. Using the computer science publication database DBLP, we
compile relations between authors and publications as graphs and proceed with
examining and quantifying collaborative relations with graph-based methods. We
review standard properties of the network and rank authors and publications by
centrality. Additionally, we detect communities with modularity-based
clustering and compare the resulting clusters to a ground-truth based on
conferences and thus topical similarity. In a second part, we are the first to
combine DBLP network data with data from the Dagstuhl Seminars: We investigate
whether seminars of this kind, as social and academic events designed to
connect researchers, leave a visible track in the structure of the
collaboration network. Our results suggest that such single events are not
influential enough to change the network structure significantly. However, the
network structure seems to influence a participant's decision to accept or
decline an invitation.Comment: ASONAM 2012: IEEE/ACM International Conference on Advances in Social
Networks Analysis and Minin
Predictivity of models with spontaneously broken non-Abelian discrete flavor symmetries
In a class of supersymmetric flavor models predictions are based on residual
symmetries of some subsectors of the theory such as those of the charged
leptons and neutrinos. However, the vacuum expectation values of the so-called
flavon fields generally modify the K\"ahler potential of the setting, thus
changing the predictions. We derive simple analytic formulae that allow us to
understand the impact of these corrections on the predictions for the masses
and mixing parameters. Furthermore, we discuss the effects on the vacuum
alignment and on flavor changing neutral currents. Our results can also be
applied to non--supersymmetric flavor models.Comment: 34 pages, 4 figures, related Mathematica package can be found at
http://einrichtungen.ph.tum.de/T30e/codes/KaehlerCorrections/, updated
version with added reference, matching NPB articl
Generating realistic scaled complex networks
Research on generative models is a central project in the emerging field of
network science, and it studies how statistical patterns found in real networks
could be generated by formal rules. Output from these generative models is then
the basis for designing and evaluating computational methods on networks, and
for verification and simulation studies. During the last two decades, a variety
of models has been proposed with an ultimate goal of achieving comprehensive
realism for the generated networks. In this study, we (a) introduce a new
generator, termed ReCoN; (b) explore how ReCoN and some existing models can be
fitted to an original network to produce a structurally similar replica, (c)
use ReCoN to produce networks much larger than the original exemplar, and
finally (d) discuss open problems and promising research directions. In a
comparative experimental study, we find that ReCoN is often superior to many
other state-of-the-art network generation methods. We argue that ReCoN is a
scalable and effective tool for modeling a given network while preserving
important properties at both micro- and macroscopic scales, and for scaling the
exemplar data by orders of magnitude in size.Comment: 26 pages, 13 figures, extended version, a preliminary version of the
paper was presented at the 5th International Workshop on Complex Networks and
their Application
Chapter Pretargeted Theranostics
Personalized medicine is becoming an integral part of our healthcare system, in which theranostics play a fundamental role. Nanomedicines such as monoclonal antibodies are a commonly used targeting vector in such approaches due to their outstanding targeting abilities as well as their capabilities to function as drug delivery vehicles. However, the application of nanomedicines in a clinical setting is connected with several challenges. For example, nanomedicines typically possess slow pharmacokinetics in respect to target accumulation and excretion. For targeted radionuclide therapy, this results in high radiation burden to healthy tissue. For drug delivery systems, long circulation and excretion times of the nanomedicine complicate site-specific release approaches and limit as such the usability of these strategies. One way to circumvent these challenges is the use of pretargeting strategies, which allow to separate the accumulation and excretion of nanomedicines from the actual diagnostic or therapeutic application. As such, pretargeting allows to use theranostic concepts utilizing the same nanomedicine and determine the success chances with diagnostic measures before initiating therapy. This chapter will explain the concept of pretargeted theranostics, which pretargeting systems have thus far been developed and compare how these systems performed
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