Observaciones microscópicas sobre los sedimentos en los manglares de El Salvador.

Los sedimentos de los manglares en El Salvador, son generalmente pobres en substancia orgánica, aunque algunos huelan fuertemente a H2S, Para los estudios siguientes puso a nuestra disposición el Prof. Dr. Weyl, material que se distinguía por su contenido en substancia orgánica, el cual era reconocible aun microscópicamente por los abundantes residuos de raíces y su color más oscuro

Teichm\"uller's problem in space

Quasiconformal homeomorphisms of the whole space Rn, onto itself normalized at one or two points are studied. In particular, the stability theory, the case when the maximal dilatation tends to 1, is in the focus. Our main result provides a spatial analogue of a classical result due to Teichm\"uller. Unlike Teichm\"uller's result, our bounds are explicit. Explicit bounds are based on two sharp well-known distortion results: the quasiconformal Schwarz lemma and the bound for linear dilatation. Moreover, Bernoulli type inequalities and asymptotically sharp bounds for special functions involving complete elliptic integrals are applied to simplify the computations. Finally, we discuss the behavior of the quasihyperbolic metric under quasiconformal maps and prove a sharp result for quasiconformal maps of R^n \ {0} onto itself.Comment: 25 pages, 2 figure

Analytical approximation of the exterior gravitational field of rotating neutron stars

It is known that B\"acklund transformations can be used to generate stationary axisymmetric solutions of Einstein's vacuum field equations with any number of constants. We will use this class of exact solutions to describe the exterior vacuum region of numerically calculated neutron stars. Therefore we study how an Ernst potential given on the rotation axis and containing an arbitrary number of constants can be used to determine the metric everywhere. Then we review two methods to determine those constants from a numerically calculated solution. Finally, we compare the metric and physical properties of our analytic solution with the numerical data and find excellent agreement even for a small number of parameters.Comment: 9 pages, 10 figures, 3 table

Open Problems on Central Simple Algebras

We provide a survey of past research and a list of open problems regarding central simple algebras and the Brauer group over a field, intended both for experts and for beginners.Comment: v2 has some small revisions to the text. Some items are re-numbered, compared to v

Apšvietimas kaip architektūros modernumo simbolis

The paper is designed to reveal the aesthetics of artificial lighting and its influence on the architecture of the 20th century. The main topics discussed are electric lighting, which appeard in our history at the end of the 19th century, and the technical development of lighting till the middle of the 20th century. Connections of artificial lighting with visual arts, its influence on advertisement, building architecture and the whole city are analysed. An idea is proposed that although lighting by nature was purely functional, very soon it acquired symbolic ambitions to represent architecture. In modern times architects understood that lighting was both a technological development and a symbol of a new era, when there appeared an independent field of creation - lighting architecture. Santrauka Straipsnyje nagrinėjama dirbtinio apšvietimo estetika ir jos įtaka XX a. architektūrai. Išryškinta XIX a. pabaigoje atsiradusio elektrinio apšvietimo svarba ir atskleista apšvietimo techninė raida iki XX a. vidurio. Nagrinėjamos dirbtinio apšvietimo sąsajos su vizualiaisiais menais, apšvietimo įtaka reklamai, pastatų architektūrai bei visam miestui. Straipsnyje keliama idėja, kad nors apšvietimo prigimtis pradžioje buvo grynai funkcionali, ji greitai įgavo simbolinių ambicijų – reprezentuoti architektūrą. Architektai į apšvietimą žvelgė ne tik kaip į technologinę pažangą, tai buvo naują erą ženklinantis simbolis, erą, kurioje atsiranda didelės įtakos visoms kūrybinėms idėjoms turinti nauja savarankiška kūrybos sritis – šviesos architektūra. First Published Online: 22 May 2013 Reikšminiai žodžiai: meninis, dirbtinis, elektrinis apšvietimas, stiklo, šviesos architektūra, modernumas