405 research outputs found
Asynchronous iterative computations with Web information retrieval structures: The PageRank case
There are several ideas being used today for Web information retrieval, and
specifically in Web search engines. The PageRank algorithm is one of those that
introduce a content-neutral ranking function over Web pages. This ranking is
applied to the set of pages returned by the Google search engine in response to
posting a search query. PageRank is based in part on two simple common sense
concepts: (i)A page is important if many important pages include links to it.
(ii)A page containing many links has reduced impact on the importance of the
pages it links to. In this paper we focus on asynchronous iterative schemes to
compute PageRank over large sets of Web pages. The elimination of the
synchronizing phases is expected to be advantageous on heterogeneous platforms.
The motivation for a possible move to such large scale distributed platforms
lies in the size of matrices representing Web structure. In orders of
magnitude: pages with nonzero elements and bytes
just to store a small percentage of the Web (the already crawled); distributed
memory machines are necessary for such computations. The present research is
part of our general objective, to explore the potential of asynchronous
computational models as an underlying framework for very large scale
computations over the Grid. The area of ``internet algorithmics'' appears to
offer many occasions for computations of unprecedent dimensionality that would
be good candidates for this framework.Comment: 8 pages to appear at ParCo2005 Conference Proceeding
Model bicategories and their homotopy bicategories
We give the definitions of model bicategory and -homotopy, which are
natural generalizations of the notions of model category and homotopy to the
context of bicategories. For any model bicategory , denote by
the full sub-bicategory of the fibrant-cofibrant objects. We
prove that the 2-dimensional localization of at the weak
equivalences can be computed as a bicategory \mathcal{H}\mbox{o}(\mathcal{C})
whose objects and arrows are those of and whose 2-cells are
classes of -homotopies up to an equivalence relation. The pseudofunctor
\mathcal{C} \stackrel{r}{\longrightarrow} \mathcal{H}\mbox{o}(\mathcal{C})
which yields the localization is constructed by using a notion of
fibrant-cofibrant replacement in this context. When considered for a model
category, the results in this article give in particular a bicategory whose
reflection into categories is the usual homotopy category constructed by
Quillen.Comment: 37 pages, many elevator calculus diagrams. This is a "preliminary
version
I like what you are saying, but only if i feel safe: Psychological safety moderates the relationship between voice and perceived contribution to healthcare team effectiveness
Introduction:
Are nurses who voice work-related concerns viewed as positive contributors to a team? We propose that the extent to which healthcare professionals consider voice by nurses as helpful for the team depends on how psychologically safe they feel. Specifically, we hypothesized that psychological safety moderates the relationship between voice of a lower ranking team member (i.e., a nurse) and perceived contribution by others, such that voice is more likely to be seen as valuable for team decision-making when psychological safety is high but not when it is low.
Methods:
We tested our hypotheses with a randomized between-subjects experiment using a sample of emergency medicine nurses and physicians. Participants evaluated a nurse who either did or did not speak up with alternative suggestions during emergency patient treatment.
Results:
Results confirmed our hypotheses: At higher levels of psychological safety the nurse’s voice was considered as more helpful than withholding of voice for team decision-making. This was not the case at lower levels of psychological safety. This effect was stable when including important control variables (i.e., hierarchical position, work experience, gender).
Discussion:
Our results shed light on how evaluations of voice are contingent on perceptions of a psychologically safe team context
- …