8,651 research outputs found

    Computing Matveev's complexity via crystallization theory: the boundary case

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    The notion of Gem-Matveev complexity has been introduced within crystallization theory, as a combinatorial method to estimate Matveev's complexity of closed 3-manifolds; it yielded upper bounds for interesting classes of such manifolds. In this paper we extend the definition to the case of non-empty boundary and prove that for each compact irreducible and boundary-irreducible 3-manifold it coincides with the modified Heegaard complexity introduced by Cattabriga, Mulazzani and Vesnin. Moreover, via Gem-Matveev complexity, we obtain an estimation of Matveev's complexity for all Seifert 3-manifolds with base D2\mathbb D^2 and two exceptional fibers and, therefore, for all torus knot complements.Comment: 27 pages, 14 figure

    A combinatorial smoothness criterion for spherical varieties

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    We suggest a combinatorial criterion for the smoothness of an arbitrary spherical variety using the classification of multiplicity-free spaces, generalizing an earlier result of Camus for spherical varieties of type AA.Comment: 14 pages, 2 table

    Compact 3-manifolds via 4-colored graphs

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    We introduce a representation of compact 3-manifolds without spherical boundary components via (regular) 4-colored graphs, which turns out to be very convenient for computer aided study and tabulation. Our construction is a direct generalization of the one given in the eighties by S. Lins for closed 3-manifolds, which is in turn dual to the earlier construction introduced by Pezzana's school in Modena. In this context we establish some results concerning fundamental groups, connected sums, moves between graphs representing the same manifold, Heegaard genus and complexity, as well as an enumeration and classification of compact 3-manifolds representable by graphs with few vertices (≤6\le 6 in the non-orientable case and ≤8\le 8 in the orientable one).Comment: 25 pages, 11 figures; changes suggested by referee: references added, figure 2 modified, results about classification of the manifolds in Proposition 17 announced at the end of section 9. Accepted for publication in RACSAM. The final publication is available at Springer (see DOI

    Tumour-induced osteomalacia: 18 months of 2-weekly burosumab treatment

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    Summary: Tumour-induced osteomalacia (TIO) is due to an overproduction of fibroblast growth factor 23 (FGF23) by mesenchymal tumours, causing hypophosphatemia, osteomalacia and muscle weakness. TIO is usually cured by tumour resection, but neoplasms may be unidentifiable and unresectable or the patient may refuse surgery. In these cases, medical treatment with oral phosphate and calcitriol is mandatory, but it is not fully effective and it is associated with low compliance. Burosumab, a human MAB against FGF23 employed to treat X-linked hypophosphatemia (XLH), has recently been approved for TIO in the USA. Maximum burosumab dose in XLH is 90 mg administered for 2 weeks; there are no data on clinical efficacy and safety of this dose in TIO. We reported the case of a 73 years old male with multiple non-traumatic fractures, low bone mineral density, pain and reduced independence of activities of daily living. Biochemical evaluation showed hypophosphatemia, high alkaline phosphatase (ALP) and C-terminal telopeptide (CTX) and normal albumin-corrected total calcium and parathyroid hormone. Tubular phosphate reabsorption was low (80%), whereas C-terminal tail of FGF23 (cFGF23) was elevated. A 68Ga-DOTATOC PET was performed, identifying a lesion in the first left rib. The patient refused surgery; therefore, burosumab therapy was started. After 18 months of treatment (maximum dose: 60 mg administered for 2 weeks), plasma phosphate normalized and ALP levels improved (138 U/L). Patient clinical symptoms as well as pain severity and fatigue improved. Neither adverse events nor tumour progression was reported during follow-up except for a painless fracture of the second right rib. Learning points: Our case shows efficacy and safety of burosumab treatment administered every 2 weeks in a tumour-induced osteomalacia (TIO) patient. After 18 months of treatment at a maximum dose of 60 mg every 2 weeks, we found plasma phosphate normalization and ALP reduction as well as improvement in clinical symptoms and fatigue. Neither adverse events nor tumour progression was reported during follow-up, except for a painless fracture of the second right rib

    Prevention of clostridium difficile infection and associated diarrhea: An unsolved problem

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    For many years, it has been known that Clostridium difficile (CD) is the primary cause of health-care-associated infectious diarrhea, afflicting approximately 1% of hospitalized patients. CD may be simply carried or lead to a mild disease, but in a relevant number of patients, it can cause a very severe, potentially fatal, disease. In this narrative review, the present possibilities of CD infection (CDI) prevention will be discussed. Interventions usually recommended for infection control and prevention can be effective in reducing CDI incidence. However, in order to overcome limitations of these measures and reduce the risk of new CDI episodes, novel strategies have been developed. As most of the cases of CDI follow antibiotic use, attempts to rationalize antibiotic prescriptions have been implemented. Moreover, to reconstitute normal gut microbiota composition and suppress CD colonization in patients given antimicrobial drugs, administration of probiotics has been suggested. Finally, active and passive immunization has been studied. Vaccines containing inactivated CD toxins or components of CD spores have been studied. Passive immunization with monoclonal antibodies against CD toxins or the administration of hyperimmune whey derived from colostrum or breast milk from immunized cows has been tried. However, most advanced methods have significant limitations as they cannot prevent colonization and development of primary CDI. Only the availability of vaccines able to face these problems can allow a resolutive approach to the total burden due to this pathogen

    Astrophysical S factor for the radiative capture 12N(p,gamma)13O determined from the 14N(12N,13O)13C proton transfer reaction

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    The cross section of the radiative proton capture reaction on the drip line nucleus 12N was investigated using the Asymptotic Normalization Coefficient (ANC) method. We have used the 14N(12N,13O)13C proton transfer reaction at 12 MeV/nucleon to extract the ANC for 13O -> 12N + p and calculate from it the direct component of the astrophysical S factor of the 12N(p,gamma)13O reaction. The optical potentials used and the DWBA analysis of the proton transfer reaction are discussed. For the entrance channel, the optical potential was inferred from an elastic scattering measurement carried out at the same time with the transfer measurement. From the transfer, we determined the square of the ANC, C^2(13Og.s.) = 2.53 +/- 0.30 fm-1, and hence a value of 0.33(4) keVb was obtained for the direct astrophysical S factor at zero energy. Constructive interference at low energies between the direct and resonant captures leads to an enhancement of Stotal(0) = 0.42(5) keVb. The 12N(p,gamma)13O reaction was investigated in relation to the evolution of hydrogen-rich massive Population III stars, for the role that it may play in the hot pp-chain nuclear burning processes, possibly occurring in such objects.Comment: 15 pages, 10 figures, 3 tables submitted to Phys. Rev.

    Avaliação de protocolos para extração de DNA de Larvas individuais de helmintos.

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    A genotipagem de helmintos, parasitas do trato gastrintestinal de ruminantes, permite o conhecimento de polimorfismos moleculares relacionados a características adaptativas, dentre as quais se destaca a resistência a produtos anti-helmínticos. Uma vez que a determinação da freqüência gênica e da freqüência aléIica para os polimorfismos de interesse requer a avaliação individual dos helmintos, dificuldades técnicas têm sido encontradas para a recuperação de quantidade suficiente de DNA a partir de larvas para a aplicação de técnicas moleculares. Dessa maneira, o objetivo deste trabalho foi avaliar diferentes protocolos para a extração de DNA de larvas individuais de helmintos Haemonchus contortus e Trichostrongylus colubriformis no estádio L3. Após cultura de fezes de ovinos, por sete dias, as larvas de helmintos foram recuperadas e destinadas á extração de DNA

    Evaluation of autonomous mowers weed control effect in globe artichoke field

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    The development of a fully automated robotic weeder is currently hindered by the lack of a reliable technique for weed-crop detection. Autonomous mowers moving with random trajectories rely on simplified computational resources and have shown potential when applied for agricultural purposes. This study aimed to evaluate the applicability of these autonomous mowers for weed control in globe artichoke. A first trial consisting of the comparison of the performances of three different autonomous mowers (AM1, AM2 and AM3) was carried out evaluating percentage of area mowed and primary energy consumption. The most suitable autonomous mower was tested for its weed control effect and compared with a conventional weed management system. Average weeds height, weed cover percentage, above-ground weed biomass, artichoke yield, primary energy consumption and cost were assessed. All the autonomous mowers achieved a percentage of area mowed around the 80% after 180 min. AM2 was chosen as the best compromise for weed control in the artichoke field (83.83% of area mowed after 180 min of mowing, and a consumption of 430.50 kWh ha1 year1). The autonomous mower weed management achieved a higher weed control effect (weed biomass of 71.76 vs. 143.67 g d.m. m2), a lower energy consumption (430.5 vs. 1135.13 kWh ha1 year1), and a lower cost (EUR 2601.84 vs. EUR 3661.80 ha1 year1) compared to the conventional system
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