We study the boundedness and compactness of the differences of two weighted composition operators acting from the Bloch space B to the space H∞ of bounded analytic functions on the open unit disk. Such a study has a relationship to the topological structure problem of composition operators on H∞. Using this relation, we will estimate the operator norms and the essential norms of the differences...

A function theoretic characterization is given of when a composition operator is compact on BMOA, the space of analytic functions on the unit disk having radial limits that are of bounded mean oscillation on the unit circle. When the symbol of the composition operator is univalent, compactness on BMOA is shown to be equivalent to compactness on the Bloch space, and a characterization in terms o...

Catanese surfaces are regular surfaces of general type with pg = 0. They specialize to double covers of Barlow surfaces. We prove that the CH0 group of a Catanese surface is equal to Z, which implies the same result for the Barlow surfaces.

We consider a particle of half-integer spin which is nonrelativistic in the rest frame. Assuming the particle is completely polarized along third axis we calculate the Bloch vector as seen by a moving observer. The result for its length is expressed in terms of dispersion of some vector operator linear in momentum. The relation with the localization properties is discussed. ∗supported by the Ló...

In one of the Father Brown short-stories, G.K. Chesterton described the (fictitious) French detective Aristide Valentin by writing that ‘‘(h)e was not ‘a thinking machine’; for that is a brainless phrase of modern fatalism and materialism. A machine only is a machine because it cannot think.’’ Although this aphorism dates from 1911, long before the notion of a thinking machine became popular, i...

<p class="abstrak"><em>This</em><em> study aims to determine women's views on verbal sexual harassment in terms of cognitive, affective, and conative factors. This is due the increasing number acts that occur against women, one which public sphere. Forms occurred form whistling, negative speech, seduction, comments, sharp stares at body parts, or physical abuse The resea...

Introduction: Prostate cancer (PCa) is the most prevalent malignant tumor in the male population worldwide and it is the second leading cause of cancer-related death in males. PCa is almost incurable due to the resistance of PCa to conventional treatments. Cancer stem cells (CSCs) theory suggests that a small subpopulation of cancer cells is responsible for tumor development, ...