Helix surfaces in the special linear group

We characterize helix surfaces (constant angle surfaces) in the special linear group $\mathrm{SL}(2,\r)$. In particular, we give an explicit local description of these surfaces in terms of a suitable curve and a 1-parameter family of isometries of $\mathrm{SL}(2,\r)$.Comment: Minor corrections. To appear in Annali di Matematica Pura e Applicata. arXiv admin note: substantial text overlap with arXiv:1206.127

Aspergillus species in Vitis vinifera of organic and conventional farming in the São Francisco Valley, Brazil.

The biodiversity of filamentous fungi is one of the most important contributions to the occurrence of mycotoxins in agricultural products. The fungi species belonging to the genus Aspergillus has been blamed for the presence of mycotoxins in wine. The incidence of fungi of these genera in grapes will depend on climatic conditions, grape variety, form of cultivation and agricultural practices. This study aimed to identify Aspergillus species isolated from wine grapes from organic and conventional cultivation Sub-medium region of the São Francisco Valley. Varieties evaluated were Touriga Nacional and Ruby Cabernet in conventional farming and Tempranillo in organic farming

The filamentous fungi culture collection of the Department of Food Science (CCDCA), Federal University of Lavras, Brazil

Brazil has one of the highest levels of biological diversity due to its large geographical area, high coverage by rainforests, and endemic biomes, such as the Brazilian Atlantic Forest, Cerrado and Caatinga. Of the estimated 1.5 million species of fungi only 5% are known. Much of this unknown biodiversity is in the tropics, which is seriously threatened by some agricultural activities, reinforcing the urgent need for biodiversity studies in these areas. The maintenance and preservation of fungal cultures are important elements for such a requirment. The establishment of a culture collection of filamentous fungi in the Mycotoxins and Mycology Laboratory, Department of Food Science (CCDCA), Federal University of Lavras (UFLA) commenced from the bases of species maintenance, taxonomy, biotechnology and toxigenicity. The laboratory was established in 2007 to preserve potentially mycotoxigenic fungi, especially ochratoxin A and aflatoxins producers, which were isolated from food. Currently the CCDCA has more than 1000 isolates of Aspergillus, Penicillium, Cladosporium, Fusarium, Alternaria, Chaetomium, Mucor, Eurotium, and Neosartorya. A total of 66 species are represented which were isolated from food, cave environments, and soils of the Brazilian Atlantic Forest, Cerrado and Caatinga. A total of 328 cultures are preserved and maintained by periodic subculture, 137 by mineral oil preservation, and 550 by filter paper preservation. The staff trains graduate students in the taxonomy of major taxa of importance to agricultural research and food science. Finally, the CCDCA and UFLA, Brazil, in collaboration with the IBB-Biological Engineering Centre, Micoteca da Universidade do Minho, Portugal, intend to develop a project on polyphasic studies of Aspergillus and Penicillium isolated from various substrates, sources, and environments in Brazil. To pursue this aim CCDCA intends to: a) preserve Aspergillus and Penicillium strains for comparative studies between Brazilian regions and worldwide; b) foster the study of Aspergillus and Penicillium for biotechnological and toxigenic potential, and training in identification, preservation and distribution; c) establish quality control of fungal assays; and d) establish the CCDCA as a member of the global network of culture collections and participate in the international forums and organisations related to culture collections

A Small Mammal Community in a Forest Fragment, Vegetation Corridor and Coffee Matrix System in the Brazilian Atlantic Forest

The objective of our work was to verify the value of the vegetation corridor in the conservation of small mammals in fragmented tropical landscapes, using a model system in the southeastern Minas Gerais. We evaluated and compared the composition and structure of small mammals in a vegetation corridor, forest fragments and a coffee matrix. A total of 15 species were recorded, and the highest species richness was observed in the vegetation corridor (13 species), followed by the forest fragments (10) and the coffee matrix (6). The absolute abundance was similar between the vegetation corridor and fragments (F = 22.94; p = 0.064), and the greatest differences occurred between the vegetation corridor and the matrix (F = 22.94; p = 0.001) and the forest fragments and the matrix (F = 22.94; p = 0.007). Six species showed significant habitat preference possibly related to the sensitivity of the species to the forest disturbance. Marmosops incanus was the species most sensitive to disturbance; Akodon montensis, Cerradomys subflavus, Gracilinanus microtarsus and Rhipidomys sp. displayed little sensitivity to disturbance, with a high relative abundance in the vegetation corridor. Calomys sp. was the species least affected by habitat disturbance, displaying a high relative abundance in the coffee matrix. Although the vegetation corridors are narrow (4 m width), our results support the hypothesis in which they work as a forest extension, share most species with the forest fragment and support species richness and abundance closer to forest fragments than to the coffee matrix. Our work highlights the importance and cost-effectiveness of these corridors to biodiversity management in the fragmented Atlantic Forest landscapes and at the regional level

Magnetic frustration in low-dimensional substructures of hulsite Ni5.15Sn0.85(O2BO3)2

CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPERJ - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIROFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOThis paper presents an extensive study of the structural, magnetic, and thermodynamic properties of the hulsite Ni5.15Sn0.85(O2BO3)(2). The crystal structure of the hulsite has two planar substructures formed by Ni and Sn atoms: one with rectangular configuration and the other with a triangular arrangement. These substructures are linked by the boron ions and by Ni in another site closer to the rectangular arrangement, resulting in a quasi-two-dimensional character. Thus, this system literally adds a new dimension to the study of oxyborates. Our results point to a complex magnetic behavior consistent with these substructures. The planes with rectangular arrangement form a complex magnetic ordering at 180 K (one of the highest magnetic transitions among the oxyborates). The other subsystem, formed by Ni atoms located in a two-dimensional triangular lattice, does not order down to temperatures as low as 3 K. The experimental results suggest a spin-liquid behavior for this subsystem. The magnetic moments of the ions between these planes also freeze at low temperatures. The two magnetic planes coexist as independent subsystems down to the lowest temperatures of our experiments.985110CNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPERJ - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIROFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOFAPERJ - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DO RIO DE JANEIROFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAUL

Influence of physical and chemical characteristics of wine grapes on the incidence of Penicillium and Aspergillus fungi in grapes and ochratoxin A in wines

The incidence of filamentous fungi and toxin levels in grapes and wines varies depending on the variety of grapes, the wine region, agricultural practices, weather conditions, the harvest and the winemaking process. In this sense, the objective of this study was to evaluate the diversity of Aspergillus and Penicillium fungi isolated fromwine grapes of the semi-arid tropical region of Brazil, evaluate the presence of ochratoxin A (OTA) in the experimental wine and verify if there is a correlation between occurrence of these fungi and the physicochemical characteristics of the wine grapes grown in the region. For the isolation of fungi we used the direct plating technique. The presence of OTA in the experimental wine was detected by high-performance liquid chromatography. The species found were Aspergillus niger, A. carbonarius, A. aculeatus, A. niger Aggregate, A. flavus, A. sojae, Penicillium sclerotiorum, P. citrinum, P. glabrum, P. decumbens, P. solitum and P. implicatum. All isolates of A. carbonarius were OTA producers and all P. citrinum were citrinin producers. The highest concentration of OTA was found in red wine (0.29 ?g/L). All species identified in this study, except A. flavus, showed a positive correlation with at least one physicochemical parameter assessed, highlighting the pectin content, total sugar, total acidity and phenolic compounds

Thermal stability and magnetic properties of FeSiB amorphous alloy

It is well known that magnetic amorphous materials, in particular the commercial metallic glass ribbons, have good soft magnetic properties, such as: low coercivity, high magnetic saturation field, and high magnetic permeability. However, these properties change significantly when these materials undergo thermal treatments. For these reasons, the study and controlling of thermal stability of such alloys are key questions for sensor applications. In this work we have investigated the thermal and magnetic properties of the Fe78B13Si9 metallic glass.Facultad de Ciencias Exacta

Fungos ocratoxigênicos em uvas viníferas Syrah cultivadas no Vale do Submédio São Francisco.

O objetivo do presente estudo foi isolar e identificar espécies de fungos potencialmente produtores de OTA em uvas Syrah cultivadas no Vale do Submédio São Francisco, bem como avaliar a capacidade produtora desses fungos

Incidência de fungos ocratoxigênicos em uvas destinadas a produção de vinhos do Nordeste brasileiro.

O presente estudo teve como objetivo avaliar a incidência de fungos Aspergillus em uvas viníferas (Alicante Bouschet), cultivadas no Nordeste brasileiro