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Hierarchical structures play a central role in many aspects of human cognition, prominently including both language and music. In this study we addressed hierarchy in the visual domain, using a novel paradigm based on fractal images. Fractals are self-similar patterns generated by repeating the same simple rule at multiple hierarchical levels. Our hypothesis was that the brain uses different resources for processing hierarchies depending on whether it applies a "fractal" or a "non-fractal" cognitive strategy. We analyzed the neural circuits activated by these complex hierarchical patterns in an event-related fMRI study of 40 healthy subjects. Brain activation was compared across three different tasks: a similarity task, and two hierarchical tasks in which subjects were asked to recognize the repetition of a rule operating transformations either within an existing hierarchical level, or generating new hierarchical levels. Similar hierarchical images were generated by both rules and target images were identical. We found that when processing visual hierarchies, engagement in both hierarchical tasks activated the visual dorsal stream (occipito-parietal cortex, intraparietal sulcus and dorsolateral prefrontal cortex). In addition, the level-generating task specifically activated circuits related to the integration of spatial and categorical information, and with the integration of items in contexts (posterior cingulate cortex, retrosplenial cortex, and medial, ventral and anterior regions of temporal cortex). These findings provide interesting new clues about the cognitive mechanisms involved in the generation of new hierarchical levels as required for fractals.

The Thiarid snail Melanoides tuberculatus (Müller, 1774), native to Asia and East Africa was recorded for the first time in the Paranã River basin, Goiás State. There is no evidence concerning introduction vectors but aquarium releases is the most probable vector. Specimens were collected at three different water bodies after twenty-seven rivers were investigated. The possible spread of this species to other habitats and potential effects on native thermal water communities are discussed. O gastrópode Thiaridae Melanoides tuberculatus (Müller, 1774), nativo da Ásia e do Leste Africano, é registrado pela primeira vez na Bacia Hidrográfica do Rio Paranã (Estado de Goiás). Não se conhecem os vetores de introdução da espécie, mas o setor de aquariofilia foi apontado por alguns moradores locais como a mais provável causa. Os espécimes foram coletados em três corpos d´água depois de serem investigados vinte e sete rios e lagoas. A possibilidade de dispersão dessa espécie para outros habitats e os efeitos potenciais dessa introdução sobre a comunidade nativa são discutidos no artigo.

We present an algebraic Bethe ansatz for certain submanifolds of the bilayer vertex models proposed by Shiroishi and Wadati as coupled asymmetric six-vertex free-fermion models. A peculiar feature of our formulation is the presence of a diagonal monodromy matrix element that does not generate unwanted terms. The model contains two free-parameters entering into the Bethe ansatz equations as a pure phase factor., Latex, 11 pages

To study the distribution of molluscs in the Riacho Fundo Creek (cerrado region of central Brazil), five creek sites were sampled once every two months for one year. Molluscs were sampled using standardized kick-net sampling. Four species of molluscs were found: Physella cubensis, Melanoides tuberculata, Biomphalaria straminea and Pisidium sp. The most abundant were P. cubensis and Pisidium sp. Physella cubensis was most abundant in the dry season and Pisidium sp. was most abundant in the rainy season, probably reflecting the rainy season increase of water currents.

The Bethe ansatz equations of the fundamental Sp(2N) integrable model are solved by a peculiar configuration of roots leading us to determine the nature of the excitations. They consist of N elementary generalized spinons and N-1 composite excitations made by special convolutions between the spinons. This fact is essential to determine the low-energy behaviour which is argued to be described in terms of 2N Majorana fermions. Our results have practical applications to spin-orbital systems and also shed new light to the connection between integrable models and Wess-Zumino-Witten field theories., latex, 10 pages

Data on the association of schistosomiasis and hepatitis B in field-based studies are scarce. Two areas have been selected for this study: i) Queixadinha, endemic for schistosomiasis, with a population of 693 individuals, and ii) Capao, a control non-endemic area, with 515 inhabitants. Sera of all individuals in both areas were tested for hepatitis B infection, yearly, from 1994 to 1997. In the first area hepatitis B was found in 32.1% of children up to one year old and reached a peak of 68.7% in the age range of 15 to 19 years. In the control area the prevalence of hepatitis B was under 5% up to 19 years of age and the highest prevalence was observed in adults over 45. HBsAg was detected in 9.4% of the individuals living in the endemic area for schistosomiasis and in 1.4% of the controls (OR = 4.98; 95% CI = 3.7-6.7). The index of chronicity of HBsAg was not statistically different in the studied areas (8.1% x 7.3%; OR = 1.09; 95% CI = 0.42-3.03), nor was it different for people with and without schistosomiasis in Queixadinha (8.7% x 7.0%). We conclude that the Schistosoma mansoni infection has not altered the course of hepatitis B in the studied area.

A case is reported of a patient with an asymmetric septate uterus and menstrual retention in the blind cavity localized on the right side of the septum. A review is made of the literature about this rare malformation first described by Robert, is made.

We present the exact solution of the $Osp(1|2)$ invariant magnet by the Bethe ansatz approach. The associated Bethe ansatz equation exhibit a new feature by presenting an explicit and distinct phase behaviour in even and odd sectors of the theory. The ground state, the low-lying excitations and the critical properties are discussed by exploiting the Bethe ansatz solution., 8 pages, UFSCARF-TH-12

We study the solutions of the Yang–Baxter equation associated with 19-vertex models invariant by the parity-time symmetry from the perspective of algebraic geometry. We determine the form of the algebraic curves constraining the respective Boltzmann weights and find that they possess a universal structure. This allows us to classify the integrable manifolds into four different families reproducing three known models, besides uncovering a novel 19-vertex model in a unified way. The introduction of the spectral parameter on the weights is made via the parameterization of the fundamental algebraic curve which is a conic. The diagonalization of the transfer matrix of the new vertex model and its thermodynamic limit properties are discussed. We point out a connection between the form of the main curve and the nature of the excitations of the corresponding spin-1 chains.

We discuss a class of transfer matrix built by a particular combination of isomorphic and non-isomorphic GL(N) invariant vertex operators. We construct a conformally invariant magnet co nstituted of an alternating mixture of GL(N) ``spins'' operators at different order of represent ation. The corresponding central charge is calculated by analysing the low temperature beha viour of the associated free energy. We also comment on possible extensions of our results for more general classes of mixed systems., 19 pages

Departamento de Clinica Medica, Faculdade deMedicina, UFMG, Av. Alfredo Balena190, 30130-100 Belo Horizonte, MG, Brasil*Escola de Ciencias Medicas de Alagoas, Maceio,AL, Brasil **Fundacao Nacional de Saude,Belo Horizonte, MG, BrasilKey words: schistosomiasis - Schistosoma mansoni -ultrasound - periportal fibrosis

(With 1 figure)Anodontites tenebricosus (Lea, 1834) typically inhabits lotic environments, partially buried in sandy or gravel substrate in South America waters ( Bonetto, 1967 ; Castellanos and Landoni, 1990). The species occurs in four Neotropical sub-regions, and, in Brazil, it has been mostly found in the Parana basin (Mansur and Pereira, 2006; Graf and Cummings, 2007 ; Bogan and Cummings, 2011; Troncon and Avelar, 2011).The Tocantins-Araguaia basin occupies 10.8% of Brazil, and reaches five Brazilian states and Distrito Federal. The Tocantins River rises in Goias state, Central Brazil, and its superior course is formed by two main tributaries, the rivers Maranhao and Parana. Nowadays, the water pumping for agriculture and industry uses are the mainly applications of the basin, turning critical the balance between water availability and its demand ( ANA, 2013 ).The field work was carried out at the Parana River (14° 46’ 17.89” S - 47° 20’ 18.68” W), on the surroundings of Alto Paraiso de Goias, Goias state (see Figure 1). The bivalves were collected by fishing net in September 2008, by the end of the dry season. A complete individual and three valves were identified and deposited in the Mollusk Collection of University of Brasilia (lot numbers CMUnB 417 and CMUnB 429).According to Pereira et al. (2013), A. tenebricosus occurs principally at the lower countries of South America, being recorded in the Uruguay, Plata and Parana basins, with its frequency decreasing northwards (Pereiraet al., 2013). Simone (2006) estimates its distribution along all South-American basins westerly to Andes, however, there was no record of the species in the Tocantins-Araguaia basin until now, and the Venezuelan register for the Orinoco river delta shows no connection to this hydrographic region.The Brazilian inland aquatic ecosystems are in real danger. For the range of Tocantins-Araguaia basin, the main threats to the freshwater biodiversity are poor water treatment, deforestation, construction of dams and canals, intensive cattle ranching and predatory fisheries (Tundisi, 2003). Most of these are pointed as the causes of local extirpation and extinction of many endemic species of freshwater mussels ( Bogan, 1993 ). The Brazilian Ministry of Environment (MMA) classified A. tenebricosus as “Vulnerable” (Amaral et al., 2008), but the IUCN ranks it as “Least Concern” (Bogan and Cummings, 2011). Therefore, this divergent situation urgently requires studies on freshwater mussels in the country.The new record of A. tenebricosus in the headwaters of the Tocantins River may be a sign that it can be found along the Tocantins-Araguaia basin, and this new-found data is an incentive for further fieldwork at the region. The biological and ecological features of the animal, as well as its relation with fishermen and other communities, must be investigated.