Some hydrophysical and hydrochemical parameters of the upper part of the hydrogen sulfide zone in the Black Sea, September 11-22, 1994

Features of spatial variability of hydrogen sulfide in the northeastern part of the Black Sea are estimated. Some technical aspects of H2S concentration determination in the anoxic zone are discussed: in its upper part at H2S concentration <30 µmol/l, the photometric method is recommended, while for deeper layers the iodometric method should be used. With linearity of vertical distribution of hydrogen sulfide and ammonium taken into account their vertical gradients are estimated as 0.49+/-0.04 µmol/m and 0.19+/-0.06 µmol/m respectively. It is shown that the upper boundary of the H2S layer corresponds to the isopycnal surface with Sigma_t = 16.19+/-0.05 arbitrary units. Special attention is paid to relationship of hydrogen sulfide distribution with hydrophysical features in the region under study, in particular in the coastal zone. It is shown that hydrodynamic conditions control spatial distribution of hydrogen sulfide. On the basis of isopycnal treatment of the H2S field existence of a coastal convergence zone is proved, and peculiarities are recognized of vertical circulation in the main Black Sea gyre and coastal anticyclonic eddies; here hydrogen sulfide serves as a tracer of hydrophysical mixing processes.

Crossed-arch vaults in late-gothic and early Renaissance vaulting: a problem in building technology transfer

Crossed-arch vaults are a particular type of ribbed vaults. Their main feature is that the ribs that form the vault are intertwined, forming polygons or stars and leaving an empty space in the middle. The firsts appear in Córdoba in the second half of the 10th Century. Afterwards, the type diffused through Spain and North Africa, 11th_13th Centuries. These vaults reappear in Armenia in the 13th Century. In the 14th and 15th Century a few examples are found both in England (Durham, Raby) and Central Europe (Prague, Landshut, Vienna). At about the same time, Leonardo da Vinci produced designs for the Tiburio (Ciborium) of Milan cathedral with a cross-arched structure and proposed tests to assess the strength; he also, made use of the same pattern of vault for Renaissance centralized churches. Eventually, the type can be tracked through the 17th (Guarini) and 18th (Vittone) Centuries, until Spanish post war architecture in the 1940-60s (Moya). Some questions arose, which so far, have not been answered. How was it possible that a particular type of vault had such enormous geographical spread? How was it transmitted from Córdoba to the Caucasus? The matter is one of transfer of knowledge, ideas, and technology; it relates both aesthetics and construction.

El juego estratégico de Rusia en el Cáucaso Sur: Sochi 2014

La propuesta de la ciudad de Sochi como sede de los Juegos Olímpicos de Invierno y de la 16° fecha del Gran Premio de Fórmula 1 de 2014, y como una de las sedes de la futura Copa Mundial de Futbol 2018, son una ratificación de la importancia estratégica que representa el Cáucaso para Rusia. Asimismo, el anclaje en el Cáucaso y en las costas del Mar Negro, con toda la inversión en infraestructura y en seguridad que representa la organización de eventos deportivos mundiales, implica la puesta en juego de una estrategia geopolítica que expresa la importancia de Rusia como potencia regional. En el calidoscopio de poder e intereses que se despliegan en la región caucásica, la sombra de Rusia se proyecta con fuerza. Abordar el rol que ejerce este país en el Cáucaso Sur, permitirá comprender las perspectivas actuales de la política exterior de Rusia en esta región, así como conocer de qué modo se despliega en el territorio el juego estratégico del poder a través de eventos deportivos que se observan desde todos los lugares del mundo.

Regnum Persicum Imperium Turcicum in Asia Russorum Provinciae ad Mare Caspium: aliaequae regiones finitimae, item Ponti Euxini, Maris Caspii, ac Sinus Persici novissimae ac fidelissimae delineationes

Reinero et Josua Ottens.

Karte der Kaukasus-Länder und der angränzenden Türkischen und Persischen Provinzen Armenien, Kurdistan, und Azerbeidjan

bearbeitet und gezeichnet von H. Kiepert.