We study the classifying problem of immersed submanifolds in Hermitian symmetric spaces. Typically in this paper, we deal with real hypersurfaces in a complex two-plane Grassmannian $G_2({\mathbb C}^{m+2})$ which has a remarkable geometric structure as a Hermitian symmetric space of rank 2. In relation to the generalized Tanaka-Webster connection, we consider a new concept of the parallel normal Jacobi operator for real hypersurfaces in $G_2({\mathbb C}^{m+2})$ and prove non-existence of real hypersurfaces in $G_2({\mathbb C}^{m+2})$ with generalized Tanaka-Webster parallel normal Jacobi operator.
Like the rest of Central and Eastern Europe, after the Second World War, Croatia came under the rule of the Communist regime. It constituted a part of the Socialist Federal Republic of Yugoslavia, in which the shift towards the Soviet model was happening faster than in the majority of countries in the region. After 1948, the Tito-Stalin split and the conflict between Yugoslavia and the Eastern Bloc the situation gradually moved towards partial liberalization, though some remnants of the Soviet model were still present, and the government’s policies towards the intellectual elite of the country continued to be marked by imposing ideology and attempts to establish control of the Communist Party. Under such conditions, the processes which occurred at the university, in the Academy of Arts and Sciences and in cultural institutions did not differ much from those found in the other countries under Communist rule, and the attitudes of individuals varied from wholehearted support for the regime, through adjustment to the situation and cooperation with the authorities, to resistance. The main scholarly institutions in Croatia at that time were the University of Zagreb and the Yugoslav Academy of Sciences and Arts. In the first period after WWII, the Yugoslav Communist regime tried to introduce the Soviet model in the field of sciences, meaning the transformation of universities into teaching institutions and concentrating the whole research processes in the institutes of the academies of sciences. This changed to some extent after the Tito-Stalin conflict, but some traces of this remained in later periods. The control of the Communist Party also remained in the form of the so-called self-management systems. Still, the Communist regime was never completely satisfied with the level of its influence on the intellectual elites and the main institution in the country. and Chorvatsko se po druhé světové válce dostalo pod kontrolu komunistického režimu stejně jako větší část střední a východní Evropy. Bylo součástí Socialistické federativní republiky Jugoslávie a tempo změn směřujících k sovětskému modelu bylo v této zemi větší než v okolních státech v regionu. Po roce 1948, kdy došlo k rozkolu mezi Titem a Stalinem, a Jugoslávie se tak ocitla v rozporu se zbytkem Východního bloku, se poměry začaly pozvolna liberalizovat, ačkoliv mnohé prvky sovětského modelu zůstávaly zachovány a vládní politika vůči intelektuálním elitám země byla nadále vedena v duchu ideové kontroly a nastolení komunistické svrchovanosti. Za těchto podmínek se prostředí univerzity, Akademie věd a umění jakož i ostatních kulturních institucí příliš nelišilo od poměrů v jiných komunisty ovládaných zemích. Postoje jednotlivců sahaly od upřímné spolupráce s režimem přes víceméně oportunní přizpůsobení se poměrům a kooperaci s vládními orgány, až po odpor. Hlavní akademické instituce Chorvatska té doby představují Záhřebská univerzita a Jugoslávská akademie věd a umění. V prvním období bezprostředně po druhé světové válce se jugoslávský komunistický režim snažil po sovětském vzoru organizovat vědu tak, že univerzity měly být transformovány na pracoviště čistě pedagogická a veškerý výzkum měl být soustředěn a veden pod záštitou ústavů Akademie věd. Tento přístup se po rozkolu Tita a Stalina poněkud změnil, avšak některé jeho prvky přetrvaly do následujících období. Komunistická strana se rovněž pokoušela o kontrolu prostřednictvím tzv. samosprávného systému, Nebyla však s rozsahem svého vlivu na inteligenci státu, jakož i na na hlavní vědecké instituce, nikdy zcela spokojena.
The surface structures and gland cells of the posterior rosette organ of Gyrocotyle urna Grube et Wagener, 1852, a member of the group presumed to be the most basal of the tapeworms (Cestoda: Gyrocotylidea), was studied by scanning electron and transmission electron microscopy. Surface structures on the outer (oriented away from the intestinal wall) and inner (in contact with the intestinal wall) rosette surfaces differ from each other and represent a transitional form between microvilli and microtriches typical of tapeworms (Eucestoda). The inner surface of the rosette possesses numerous glands. On the basis of the size and electron-density of their secretory granules, three types of unicellular gland cells can be distinguished. The least common type (Type I) is characterized by the production of small, round, electron-dense granules of about 0.3 µm in diameter, whereas another type of secretion (Type II) is formed from homogenous, moderately electron-dense, spheroidal granules of about 0.7 µm in diameter. The most common type of glands (Type III) is recognized by a secretion comprising large, elongate, electron-dense granules of about 1 µm long and 0.5 µm broad. The secretory granules of the three types of the glands are liberated by an eccrine mechanism and the gland ducts open via small pores on the inner rosette surface. The complex of secretory glands of the posterior rosette of G. urna is similar to those in the anterior attachment glands of monogeneans (as opposed to the types of glands present in other helminth groups). However, the tegumental surface structures of Gyrocotyle are supporting evidence for the relationship between the Gyrocotylidea and Eucestoda.