1,256 research outputs found
A semi-supervised approach to visualizing and manipulating overlapping communities
When evaluating a network topology, occasionally data structures cannot be segmented into absolute, heterogeneous groups. There may be a spectrum to the dataset that does not allow for this hard clustering approach and may need to segment using fuzzy/overlapping communities or cliques. Even to this degree, when group members can belong to multiple cliques, there leaves an ever present layer of doubt, noise, and outliers caused by the overlapping clustering algorithms. These imperfections can either be corrected by an expert user to enhance the clustering algorithm or to preserve their own mental models of the communities. Presented is a visualization that models overlapping community membership and provides an interactive interface to facilitate a quick and efficient means of both sorting through large network topologies and preserving the user's mental model of the structure. © 2013 IEEE
Adaptive visualization of research communities
Adaptive visualization approaches attempt to tune the content and the topology of information visualization to various user characteristics. While adapting visualization to user cognitive traits, goals, or knowledge has been relatively well explored, some other user characteristics have received no attention. This paper presents a methodology to adapt a traditional cluster-based visualization of communities to user individual model of community organization. This class of user-adapted visualization is not only achievable, but expected due to real world situation where users cannot be segmented into heterogeneous communities since many users have affinity to more than one group. An interactive clustering and visualization approach presented in the paper allows the user communicate their personal mental models of overlapping communities to the clustering algorithm itself and obtain a community visualization image that more realistically fits their prospects
On tadpoles and vacuum redefinitions in String Theory
Tadpoles accompany, in one form or another, all attempts to realize
supersymmetry breaking in String Theory, making the present constructions at
best incomplete. Whereas these tadpoles are typically large, a closer look at
the problem from a perturbative viewpoint has the potential of illuminating at
least some of its qualitative features in String Theory. A possible scheme to
this effect was proposed long ago by Fischler and Susskind, but incorporating
background redefinitions in string amplitudes in a systematic fashion has long
proved very difficult. In the first part of this paper, drawing from field
theory examples, we thus begin to explore what one can learn by working
perturbatively in a ``wrong'' vacuum. While unnatural in Field Theory, this
procedure presents evident advantages in String Theory, whose definition in
curved backgrounds is mostly beyond reach at the present time. At the field
theory level, we also identify and characterize some special choices of vacua
where tadpole resummations terminate after a few contributions. In the second
part we present a notable example where vacuum redefinitions can be dealt with
to some extent at the full string level, providing some evidence for a new link
between IIB and 0B orientifolds. We finally show that NS-NS tadpoles do not
manifest themselves to lowest order in certain classes of string constructions
with broken supersymmetry and parallel branes, including brane-antibrane pairs
and brane supersymmetry breaking models, that therefore have UV finite
threshold corrections at one loop.Comment: 51 pages, LaTeX, 7 eps figures. Typos corrected, refs added. Final
version to appear in Nucl. Phys. B. Thanks to W. Mueck for very interesting
correspondence. v3 was accidentally in draft forma
Stringy Instanton Effects in Models with Rigid Magnetised D-branes
We compute instantonic effects in globally consistent T^6/Z2xZ2 orientifold
models with discrete torsion and magnetised D-branes. We consider fractional
branes and instantons wrapping the same rigid cycles. We clarify and analyse in
detail the low-energy effective action on D-branes in these models. We provide
explicit examples where instantons induce linear terms in the charged fields,
or non-perturbative mass terms are generated. We also find examples where the
gauge theory on fractional branes has conformal symmetry at one-loop, broken by
instantonic mass terms at a hierarchically small energy scale.Comment: 60 pages. Refs added. Typos corrected in some eqs. Modified comments
in subsection 4.
Testing extra dimensions with boundaries using Newton's law modifications
Extra dimensions with boundaries are often used in the literature, to provide
phenomenological models that mimic the standard model. In this context, we
explore possible modifications to Newton's law due to the existence of an
extra-dimensional space, at the boundary of which the gravitational field obeys
Dirichlet, Neumann or mixed boundary conditions. We focus on two types of extra
space, namely, the disk and the interval. As we prove, in order to have a
consistent Newton's law modification (i.e., of the Yukawa-type), some of the
extra-dimensional spaces that have been used in the literature, must be ruled
out.Comment: Published version, title changed, 6 figure
An Order (Rlte) of Christian Initiation of Adults Handbook For Directors, Coordinators and Team Ministers
Vatican II called for a renewal of evangelization, catechesis, and liturgical celebration. The Catholic Church then wrote new rites for the Order of Christian Initiation of Adults (OCIA). To help OCIA ministers get started with group formation on the journey of faith resulting in conversion and transformation of lives, an OCIA Handbook was written that explains how best to catechize: to discuss the Scripture with a focus on life experiences and Christian responses; to incorporate the Church’s doctrines and precepts; and, to involve more parishioners in the OCIA process to welcome new members and to reinvigorate the parish congregation’s faith
Magnetized Type I Orbifolds in Four Dimensions
I review the basic features of four dimensional Z_2 x Z_2 (shift)
orientifolds with internal magnetic fields, describing two examples with N=1
supersymmetry. As in the corresponding six-dimensional examples, D9-branes
magnetized along four internal directions can mimic D5-branes, even in presence
of multiplets of image branes localized on different fixed tori. Chiral
low-energy spectra can be obtained if the model also contains D5-branes
parallel to the magnetized directions.Comment: 4 pages, LATEX; misprints correcte
Appeal No. 0888: Edco Drilling and Producing, v. Division of Oil & Gas Resources Management
Chief\u27s Order 2014-254 (Hedrick #1A Well
Gauge vs. Gravity mediation in models with anomalous U(1)'s
In an attempt to implement gauge mediation in string theory, we study string
effective supergravity models of supersymmetry breaking, containing anomalous
gauge factors. We discuss subtleties related to gauge invariance and the
stabilization of the Green-Schwarz moduli, which set non-trivial constraints on
the transmission of supersymmetry breaking to MSSM via gauge interactions.
Given those constraints, it is difficult to obtain the dominance of gauge
mediation over gravity mediation. Furthermore, generically the gauge
contributions to soft terms contain additional non-standard terms coming from
D-term contributions. Motivated by this, we study the phenomenology of recently
proposed hybrid models, where gravity and gauge mediations compete at the GUT
scale, and show that such a scenario can respect WMAP constraints and would be
easily testable at LHC.Comment: 40 pages, 5 figure
Non-tachyonic Scherk-Schwarz compactifications, cosmology and moduli stabilization
It is well-known that Scherk-Schwarz compactifications in string theory have
a tachyon in the closed string spectrum appearing for a critical value of a
compact radius. The tachyon can be removed by an appropriate orientifold
projection in type II strings, giving rise to tachyon-free compactifications.
We present explicit examples of this type in various dimensions, including six
and four-dimensional chiral examples, with softly broken supersymmetry in the
closed sector and non-BPS configurations in the open sector. These vacua are
interesting frameworks for studying various cosmological issues. We discuss
four-dimensional cosmological solutions and moduli stabilization triggered by
nonperturbative effects like gaugino condensation on D-branes and fluxes.Comment: 36 pages, LaTeX; added reference
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