2,623 research outputs found

    Noether's Symmetry Theorem for Variational and Optimal Control Problems with Time Delay

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    We extend the DuBois-Reymond necessary optimality condition and Noether's symmetry theorem to the time delay variational setting. Both Lagrangian and Hamiltonian versions of Noether's theorem are proved, covering problems of the calculus of variations and optimal control with delays.Comment: This is a preprint of a paper whose final and definite form will appear in the international journal Numerical Algebra, Control and Optimization (NACO). Paper accepted for publication 15-March-201

    Mathematical retroreflectors

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    Retroreflectors are optical devices that reverse the direction of incident beams of light. Here we present a collection of billiard type retroreflectors consisting of four objects; three of them are asymptotically perfect retroreflectors, and the fourth one is a retroreflector which is very close to perfect. Three objects of the collection have recently been discovered and published or submitted for publication. The fourth object - notched angle - is a new one; a proof of its retroreflectivity is given.Comment: 32 pages, 19 figure

    Layer-by-layer deposition of antimicrobial polymers on cellulosic fibers : a new strategy to develop bioactive textiles

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    In recent years, there has been an increase of infectious diseases caused by different microorganisms and the development of antibiotic resistance. In this way, the search for new and efficient antibacterial materials is imperative. The main polysaccharides currently used in the biomedical and pharmaceutical domains are chitin and its derivative chitosan (CH) and alginates (ALG). In this study, a simple technique of Layer by Layer (LbL) of applying polycation CH and polyanion ALG was used to prepare CH/ALG multilayers on cotton samples via the electrostatic assembly with success. The CH/ALG cotton samples (functionalized) were investigated for their antibacterial properties towards Staphylococcus aureus and Klebsiella pneumonia using the international standard method JIS L 1902:2002. The antibacterial activity of the functionalized samples was tested in terms of bacteriostatic and bactericidal activity, and results showed that the samples exhibited a bacteriostatic effect on the two bacteria tested, as expected. In addition, samples with five layers (CH/ALG/CH/ALG/CH) were more effective in inhibiting bacterial growth. This new coating for cellulosic fibers is a new strategy and may open new avenues for the development of antimicrobial polymers with potential application in health-care field.The authors would like to thank Fundacao para a Ciencia e Tecnologia (FCT) for the funding granted concerning the project - PTDC/EBB-BIO/113671/2009 (FCOMP-01-0124-FEDER-014752) Skin2Tex. Also, we would like to thank Fundo Europeu de Desenvolvimento Regional (FEDER) through COMPETE - Programa Operacional Factores de Competitividade (POFC) for the co-funding

    Effect of vineyard floor management practices on water use: A case study at a terroir of the "Dão" winegrowing region in Portugal

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    Aiming to evaluate the effect of vineyard floor management practices on water use and vine performance, a field experiment was carried out at the Dão Wine Research Station, located at Nelas, Center Portugal. The experiment was set up in 2010 in a mature vineyard planted with the red grape variety ‘Touriga Nacional’, using a 2x2 factorial design with the following treatments: inter-row soil management (permanent resident vegetation vs. soil tillage) and undervine floor management (mulch vs. herbicide). In this paper it will be presented data from 2013 growing season (four seasons after experiment setup). The volumetric soil moisture, assessed with a capacitance probe to a 1.5 m depth, showed a decreasing pattern throughout the growing season in all treatments with the resident vegetation presenting lower values as compared to the tillage treatment, while no significant differences were observed between the two undervine floor management practices. From budburst to flowering the resident vegetation treatment showed a higher soil water depletion (up to 1.5 m depth) than the tillage treatment but the relative situation was reversed during the flowering-veraison period, while no significant differences were observed during the ripening period. Vine stem water potential values showed a decreasing pattern along the season attaining very low values during September but with no significant differences between treatments. In general the soil management practices did not significantly affect vine vigor, yield and berry composition however, since these results are only from one season, further data analysis in ongoing in order to allow stronger conclusions.info:eu-repo/semantics/publishedVersio

    The antioxidants resveratrol and N-acetylcysteine enhance anthelmintic activity of praziquantel and artesunate against Schistosoma mansoni

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    Background: Treatment of schistosomiasis has relied on the anthelmintic drug praziquantel (PZQ) for more than a generation. Despite its celebrated performance for treatment and control of schistosomiasis and other platyhelminth infections, praziquantel has some shortcomings and the inability of this drug to counteract disease sequelae prompts the need for novel therapeutic strategies. Methods: Using a host-parasite model involving Biomphalaria glabrata and Schistosoma mansoni we established mechanical transformation of S. mansoni cercariae into newly transformed schistosomula (NTS) and characterized optimal culture conditions. Thereafter, we investigated the antischistosomal activity and ability of the antioxidants N-acetylcysteine (NAC) and resveratrol (RESV) to augment the performance of praziquantel and/or artesunate (AS) against larval stages of the parasite. Drug effects were evaluated by using an automated microscopical system to study live and fixed parasites and by transmission electron microscopy (TEM). Results: Transformation rates of cercariae to schistosomula reached ~ 70% when the manipulation process was optimized. Several culture media were tested, with M199 supplemented with HEPES found to be suitable for S. mansoni NTS. Among the antioxidants studied, RESV alone or combined with anthelminthic drugs achieved better results rather N-acetylcysteine (NAC). TEM observations demonstrated that the combination of AS + RESV induced severe, extensive alterations to the tegument and subtegument of NTS when compared to the constituent compounds alone. Two anthelmintic-antioxidant combinations, praziquantel-resveratrol [combination index (CI) = 0.74] and artesunate-resveratrol (CI = 0.34) displayed moderate and strong synergy, respectively. Conclusions: The use of viability markers including staining with propidium iodide increased the accuracy of drug screening assays against S. mansoni NTS. The synergies observed might be the consequence of increased action by RESV on targets of AS and PZQ and/or they may act through concomitantly on discrete targets to enhance overall antischistosomal action. Combinations of active agents, preferably with discrete modes of action including activity against developmental stages and/or the potential to ameliorate infection-associated pathology, might be pursued in order to identify novel therapeutic interventions.We express our deepest appreciation to Mrs. Maria Lurdes Delgado for expert maintenance of the schistosome life-cycle and her technical support NV acknowledges support from the Fundação para a Ciência e Tecnologia (FCT, Portugal) and FEDER (European Union) through Project Number IF/00092/2014/CP1255/CT0004. NV thanks FCT by IF position, Fundação Manuel António da Mota (FMAM, Portugal) and Pfizer Portugal for research group support. JMCC thanks FCT for UID/Multi/00211/2019 and Strategic Project UI211. PJB acknowledges support from award RO1CA164719 from the National Cancer Institute (NCI), National Institutes of Health (NIH), USA. The contents of this report are solely the responsibility of the authors and do not necessarily represent the official views of the FCT, FMAM, the NCI, or the NIH

    New lower bound for the Hilbert number in low degree Kolmogorov systems

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    Our main goal in this paper is to study the number of small-amplitude isolated periodic orbits, so-called limit cycles, surrounding only one equilibrium point a class of polynomial Kolmogorov systems. We denote by MK(n)\mathcal M_{K}(n) the maximum number of limit cycles bifurcating from the equilibrium point via a degenerate Hopf bifurcation for a polynomial Kolmogorov vector field of degree nn. In this work, we obtain another example such that MK(3)≥6 \mathcal M_{K}(3)\geq 6. In addition, we obtain new lower bounds for MK(n)\mathcal M_{K}(n) proving that MK(4)≥13\mathcal M_{K}(4)\geq 13 and MK(5)≥22\mathcal M_{K}(5)\geq 22

    On the two-dimensional rotational body of maximal Newtonian resistance

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    We investigate, by means of computer simulations, shapes of nonconvex bodies that maximize resistance to their motion through a rarefied medium, considering that bodies are moving forward and at the same time slowly rotating. A two-dimensional geometric shape that confers to the body a resistance very close to the theoretical supremum value is obtained, improving previous results.Comment: This is a preprint version of the paper published in J. Math. Sci. (N. Y.), Vol. 161, no. 6, 2009, 811--819. DOI:10.1007/s10958-009-9602-

    Validation of masonry systems for in-plane lateral loading using truss reinforcement

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    The paper presents and describes the main issues related to two building systems for modern masonry structures using truss reinforcement, currently under development at University of Minho, one based on lightweight concrete blocks and another based on reinforced concrete block masonry. Details of the experimental and numerical work carried out are addressed, together with conclusions on the performance of the system for in-plane lateral loading

    Aspectos epidemiológicos da caprinocultura cearense.

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    0 desenvolvimento da caprinocultura na regiao Nordeste do Brasil é severamente afetado por inúmeros fatores, entre eles a alta incidência de doenças. Objetivou-se conhecer o atual manejo sanitário empregado e os problemas sanitarios existentes na opiniao do criador do Ceara. 0 trabalho foi realizado nas varias regiôes criadoras de caprinos de raças leiteiras, nativas ou sem raça definida. Foram selecionadas 127 propriedades onde se aplicou um questionario. A percentagem média de mortalidade de animais foi de 22,8% e 4,6% em jovens e adultos, respectivamente. Os sinais clinicos relatados, por ordem, foram: anemia e edema de barbela (81,9% dos criatórios), diarréia (78,7%), aborto (75,6%), pododermatite (67,7%), linfadenite (66,9%), ectoparasitoses (63,8%), mamite (51,2%), pneumonia (44,9%), lesões vesiculares de pele (35,4%), ceratoconjuntivite (29,1%), problemas de ordem nervosa (26,8%), malformaçao fetal (15%), criptorquidismo (11%), prolapso de vagina/utero (11%) e artrite (8,7%). Pode-se concluir que o manejo sanitario dos caprinos desses criatórios é precario, independente do tipo de exploraçao ou regime de criaçao, a mortalidade de animais, principalmente de jovens, é considerada alta. Mesmo em criatórios com exploraçao leiteira não existe uma preocupaçao rigorosa com higiene e qualidade do leite. Epidemiological aspects of the raising goat in Ceará State, Brazil. ABSTRACT - The development of the goat raising in the Northeastern region of Brazil is hardly affected by several factors, among them, the high incidence of illness. The aim of this study was to assess the adopted sanitary management and the healthy problems according to Ceara?s goat breeders. The work was carried out in many regions of dairy and native goat raising. There were selected 127 properties where a questionnaire was applied. Mean percentage of animals? mortality was 22.8 and 4.6% for young and adult, respectively. Reported clinical signs were: anemia and dewlap edema (81.9% of the properties), diarrhea (78.7%), abortion (75.6%), foot rot (67.7%), lymphadenitis (66.9%), external parasites (63.8%), mastitis (51.2%), pneumonia (44.9%), goat pox (35.4%), keratoconjunctivitis (29.1%), nervous disorders (26.8%), fetal malformation (15%), cryptorchidism (11%), uterus/vagina prolapsed (11%), arthritis (8.7%), foot and mouth disease (2.4%) and rabies (0.8%). It could be concluded that the goats? sanitary management of those properties is precarious, independently either the exploitation way or the raising regimen; the animals? mortality, especially the youngest ones, is considered high; and even in dairy properties there is a lack of rigid worry concerning about hygiene and milk quality

    Capsule endoscopy in inflammatory bowel disease type unclassified and indeterminate colitis serologically negative

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    BACKGROUND: The value of capsule endoscopy in the setting of inflammatory bowel disease type unclassified (IBDU) and indeterminate colitis (IC) remains obscure. The aim was to evaluate the clinical impact of capsule endoscopy on IBDU/IC patients with negative serology. METHODS: Eighteen patients with long-standing IBDU (n = 14) and IC (n = 4) were enrolled to undergo a capsule endoscopy and then followed prospectively. Lesions considered diagnostic of Crohn's disease (CD) were 4 or more erosions/ulcers and/or a stricture. The median follow-up time after capsule endoscopy was 32 ± 11 months (23-54 months). RESULTS: Total enteroscopy was possible in all patients. In 2 patients the examination was normal (Group 1). In 9 patients subtle findings were observed (Group 2): focal villi denudation (n = 1) and fewer than 4 erosions/ulcers (n = 8). In 7 patients, 4 or more erosions/ulcers were detected (Group 3), leading to a diagnosis of CD. However, their treatment was not reassessed on the basis of the capsule findings. Until now, a definitive diagnosis has been achieved in 2 additional patients: 1 from Group 1 (ulcerative colitis) and another patient from Group 2 (CD), who began infliximab infusions. Nine patients remained indeterminate at follow-up. CONCLUSIONS: Although capsule endoscopy enabled the diagnosis of CD in 7 patients, in none of them was the clinical management changed. Moreover, a change in therapy due to a diagnosis of CD was made for only 1 patient, who presented nonspecific findings. Our results suggest that capsule findings are not helpful in the work-up of these patient
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