There's Something Happening Here: A Look at The California Endowment's Building Healthy Communities Initiative

In 2011, TCE commissioned PERE to help capture some of the dynamism happening in each of the sites as they were pivoting from the initial planning phase, which started in 2009, to early implementation.Our focus was on the over-arching story of BHC rather than on the narrative of each site, which would have required many more interviews, many more site visits, and many, many more pages to convey. And while we touch on some of the interactions between BHC and the communications and policy work done under the statewide umbrella of Health Happens Here, our emphasis in this report is on BHC and the sites themselves.Through the course of this research, we have become increasingly convinced that TCE is indeed onto something -- if not big, at least important. In order to clarify exactly what it is, we use a simplifying three-part storyline linked together by an overarching concept of Just Health

A community role approach to assess social capitalists visibility in the Twitter network

In the context of Twitter, social capitalists are specific users trying to increase their number of followers and interactions by any means. These users are not healthy for the service, because they are either spammers or real users flawing the notions of influence and visibility. Studying their behavior and understanding their position in Twit-ter is thus of important interest. It is also necessary to analyze how these methods effectively affect user visibility. Based on a recently proposed method allowing to identify social capitalists, we tackle both points by studying how they are organized, and how their links spread across the Twitter follower-followee network. To that aim, we consider their position in the network w.r.t. its community structure. We use the concept of community role of a node, which describes its position in a network depending on its connectiv-ity at the community level. However, the topological measures originally defined to characterize these roles consider only certain aspects of the community-related connectivity, and rely on a set of empirically fixed thresholds. We first show the limitations of these measures, before extending and generalizing them. Moreover, we use an unsupervised approach to identify the roles, in order to provide more flexibility relatively to the studied system. We then apply our method to the case of social capitalists and show they are highly visible on Twitter, due to the specific roles they hold.Comment: arXiv admin note: substantial text overlap with arXiv:1406.661

An improved kernelization algorithm for Trivially Perfect Editing

In the Trivially Perfect Editing problem one is given an undirected graph $G = (V,E)$ and an integer $k$ and seeks to add or delete at most $k$ edges in $G$ to obtain a trivially perfect graph. In a recent work, Dumas, Perez and Todinca [Algorithmica 2023] proved that this problem admits a kernel with $O(k^3)$ vertices. This result heavily relies on the fact that the size of trivially perfect modules can be bounded by $O(k^2)$ as shown by Drange and Pilipczuk [Algorithmica 2018]. To obtain their cubic vertex-kernel, Dumas, Perez and Todinca [Algorithmica 2023] then showed that a more intricate structure, so-called \emph{comb}, can be reduced to $O(k^2)$ vertices. In this work we show that the bound can be improved to $O(k)$ for both aforementioned structures and thus obtain a kernel with $O(k^2)$ vertices. Our approach relies on the straightforward yet powerful observation that any large enough structure contains unaffected vertices whose neighborhood remains unchanged by an editing of size $k$, implying strong structural properties

A Cubic Vertex-Kernel for Trivially Perfect Editing

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