Extrusion of YAG Tubes Shows that Bottom-up Processing is Not Always Optimal

Extrusion of YAG Tubes Shows that Bottom-up Processing is Not Always Optimal

Greedy Recommending Is Not Always Optimal

Recommender systems help users to find objects or documents on web sites. In many cases it is not easy to know in advance by whom and for what purpose a web site will be used. This makes it difficult for many applications to define adequate recommendations in advance. Therefore recommendations are typically generated dynamically. Recommendations are based on analysis of user data (social filter...

Event-Related Potentials of Bottom-Up and Top-Down Processing of Emotional Faces

Introduction: Emotional stimulus is processed automatically in a bottom-up way or can be processed voluntarily in a top-down way. Imaging studies have indicated that bottom-up and top-down processing are mediated through different neural systems. However, temporal differentiation of top-down versus bottom-up processing of facial emotional expressions has remained to be clarified. The present st...

Summing up evidence: one answer is not always enough.

Are meta-analyses the brave new world, or are the critics of such combined analyses right to say that the biases inherent in clinical trials make them uncombinable? Negative trials are often unreported, and hence can be missed by meta-analysts. And how much heterogeneity between trials is acceptable? A recent major criticism is that large randomised trials do not always agree with a prior meta-...

Optimal Bounds on Theta-Graphs: More is not Always Better

We present tight upper and lower bounds on the spanning ratio of a large family of θ-graphs. We show that θgraphs with 4k+2 cones (k ≥ 1 and integer) have a spanning ratio of 1 + 2 sin(θ/2), where θ is 2π/(4k + 2). We also show that θ-graphs with 4k + 4 cones have spanning ratio at least 1 + 2 tan(θ/2) + 2 tan(θ/2), where θ is 2π/(4k + 4). This is somewhat surprising since, for equal values of ...