An upward drawing of a rooted tree is a drawing such that no parents are below their children. It is ordered if the edges to children appear in prescribed order around each vertex. It is well-known that any tree has an upward (unordered) drawing with width log(n+ 1). For ordered drawings, the best-known bounds for the width for binary trees is O(logn), while for arbitrary trees it is O(2 √ ). W...

We examine a Markovian model for the price evolution of a stock, in which the probability of local upward or downward movement is arbitrarily dependent on the current price itself (and perhaps some auxiliary state information). This model directly and considerably generalizes many of the most well-studied price evolution models in classical nance, including a variety of random walk, drift and d...

Around the world, ash and thick smoke from wildfires can choke the surrounding skies. While this visible, murky mess seems to disappear with distance from the fires, polluting gases and small particles not visible to the human eye drift upward and are carried away by global air currents. Can large wildfires contribute to smog problems in distant places? Gabriele Pfister, a researcher at the Nat...

Molecular phylogenetic studies reveal that many endosymbioses between bacteria and invertebrate hosts result from ancient infections followed by strict vertical transmission within host lineages. Endosymbionts display a distinctive constellation of genetic properties including AT-biased base composition, accelerated sequence evolution, and, at least sometimes, small genome size; these features ...

PURPOSE Although the overall development of saccades in children has recently gained increasing interest, the precise characteristics of vertical saccades remain understudied. This study focused on the development of vertical saccades and their interaction with vergence movements. METHODS Thirty-one children (mean age: 7.33 ± 0.21 years) performed vertical saccades with an eccentricity of 7.5...

introduction: wind erosion is one of the most important factors in desert environments. prevailing winds can shift sand dunes and affect their accumulation and morphology. also, wind regime determines the direction of sand dune mobility in different ways. therefore, the wind regime, frequency, direction and velocity are supposed to be the most important factors to form the morphology of sand du...