70,722 research outputs found
The Effects of Halo Assembly Bias on Self-Calibration in Galaxy Cluster Surveys
Self-calibration techniques for analyzing galaxy cluster counts utilize the
abundance and the clustering amplitude of dark matter halos. These properties
simultaneously constrain cosmological parameters and the cluster
observable-mass relation. It was recently discovered that the clustering
amplitude of halos depends not only on the halo mass, but also on various
secondary variables, such as the halo formation time and the concentration;
these dependences are collectively termed assembly bias. Applying modified
Fisher matrix formalism, we explore whether these secondary variables have a
significant impact on the study of dark energy properties using the
self-calibration technique in current (SDSS) and the near future (DES, SPT, and
LSST) cluster surveys. The impact of the secondary dependence is determined by
(1) the scatter in the observable-mass relation and (2) the correlation between
observable and secondary variables. We find that for optical surveys, the
secondary dependence does not significantly influence an SDSS-like survey;
however, it may affect a DES-like survey (given the high scatter currently
expected from optical clusters) and an LSST-like survey (even for low scatter
values and low correlations). For an SZ survey such as SPT, the impact of
secondary dependence is insignificant if the scatter is 20% or lower but can be
enhanced by the potential high scatter values introduced by a highly correlated
background. Accurate modeling of the assembly bias is necessary for cluster
self-calibration in the era of precision cosmology.Comment: 13 pages, 5 figures, replaced to match published versio
Hadronization Approach for a Quark-Gluon Plasma Formed in Relativistic Heavy Ion Collisions
A transport model is developed to describe hadron emission from a strongly
coupled quark-gluon plasma formed in relativistic heavy ion collisions. The
quark-gluon plasma is controlled by ideal hydrodynamics, and the hadron motion
is characterized by a transport equation with loss and gain terms. The two sets
of equations are coupled to each other, and the hadronization hypersurface is
determined by both the hydrodynamic evolution and the hadron emission. The
model is applied to calculate the transverse momentum distributions of mesons
and baryons, and most of the results agree well with the experimental data at
RHIC.Comment: 16 pages, 24 figures. Version accepted by PR
Robust H-infinity filtering for 2-D systems with intermittent measurements
This paper is concerned with the problem of robust H∞ filtering for uncertain two-dimensional (2-D) systems with intermittent measurements. The parameter uncertainty is assumed to be of polytopic type, and the measurements transmission is assumed to be imperfect, which is modeled by a stochastic variable satisfying the Bernoulli random binary distribution. Our attention is focused on the design of an H∞ filter such that the filtering error system is stochastically stable and preserves a guaranteed H∞ performance. This problem is solved in the parameter-dependent framework, which is much less conservative than the quadratic approach. By introducing some slack matrix variables, the coupling between the positive definite matrices and the system matrices is eliminated, which greatly facilitates the filter design procedure. The corresponding results are established in terms of linear matrix inequalities, which can be easily tested by using standard numerical software. An example is provided to show the effectiveness of the proposed approac
Semantic Wide and Deep Learning for Detecting Crisis-Information Categories on Social Media
When crises hit, many flog to social media to share or consume information related to the event. Social media posts during crises tend to provide valuable reports on affected people, donation offers, help requests, advice provision, etc. Automatically identifying the category of information (e.g., reports on affected individuals, donations and volunteers) contained in these posts is vital for their efficient handling and consumption by effected communities and concerned organisations. In this paper, we introduce Sem-CNN; a wide and deep Convolutional Neural Network (CNN) model designed for identifying the category of information contained in crisis-related social media content. Unlike previous models, which mainly rely on the lexical representations of words in the text, the proposed model integrates an additional layer of semantics that represents the named entities in the text, into a wide and deep CNN network. Results show that the Sem-CNN model consistently outperforms the baselines which consist of
statistical and non-semantic deep learning models
A History of Flips in Combinatorial Triangulations
Given two combinatorial triangulations, how many edge flips are necessary and
sufficient to convert one into the other? This question has occupied
researchers for over 75 years. We provide a comprehensive survey, including
full proofs, of the various attempts to answer it.Comment: Added a paragraph referencing earlier work in the vertex-labelled
setting that has implications for the unlabeled settin
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