Lump-like Structures in Scalar-field Models

In this work we investigate the presence of lump-like solutions in models described by a single real scalar field. We take advantage of a procedure recently used to describe explicit analytical solutions and we study several distinct models, showing how the parameters can be used to control the specific features of the lump-like structures. The proposed models are of direct interest to the construction of q-balls, to induce tachyonic excitations and gravitating structures of nontopological profile on braneworld models with a single extra dimension, to map solitons in optical fibers, and to describe collective excitations in Bose-Einstein condensates.Comment: 7 pages, 11 figure

Avaliação do efeito de veranico na produção de matéria seca de milho e sorgo.

O presente trabalho teve como principal objetivo a influencia de veranicos nas fases inicial e reprodutiva na producao de materia seca de milho e sorgo. O ensaio foi instalado em um latossolo Vermelho-Escuro,distrofico, fase cerrado, durante os anos agricolas de 1982 a 1985. No primeiro ano aplicou-se 3,7 toneladas de calcario dolomitico e fez-se uma adubacao de correcao baseada em analises do solo. As cultivares de milho utilizadas foram BR 126 e CMSXS 201 Xe, as de sorgo, BR 505 e BR 601. Em cada ano agricola estes hibridos foram plantados em 4 diferentes epocas (8, 15 e 25 de outubro e 5 de novembro), com e sem irrigacao suplementar. O delineamento experimental utilizado foi blocos casualizados com 5 repeticoes. Quantificou-se a materia seca correspondente a parte aerea das plantas colhidas quando os graos encontravam-se na fase de grao macio. Embora os resultados tenham mostrado tanto para o milho como para o sorgo, que as producoes entre anos, nao diferiram significativamente, houve um aumento medio da producao das culturas irrigadas sobre as nao irrigadas de 12 a 27% para o milho e cerca de 36% para o sorgo. Estas diferencas podem ser atribuidas a ocorrencia de veranico durante o ciclo das culturas. A producao de milho foi superior a do sorgo, principalmente quando foi utilizada irrigacao suplementar Embora a ocorrencia de veranico na fase inicial de crescimento tenha influenciado na producao de ambas as culturas, o sorgo demonstrou-se mais sensivel ao deficit de agua ate 20 a 25 dias

Sfp1 and Rtg3 reciprocally modulate carbon source-conditional stress adaptation in the pathogenic yeast Candida albicans

Acknowledgements We thank Aaron Mitchell, Dominique Sanglard and Suzanne Noble for their generosity in providing mutant collections, and Linghuo Jiang for generously providing strains. We also thank Susan Budge for her support and excellent technical assistance. We also thank the qPCR Facility in the Institute of Medical Sciences, and particularly Fiona Saunders for her great advice and help. SLK was supported by a PhD scholarship from the University of Aberdeen. AJPB was supported by the UK Biotechnology and Biological Research Council (BB/F00513X/1; BB/K017365/1), by the European Research Council (STRIFE Advanced Grant; ERC-2009-AdG-249793), and by the UK Medical Research Council (MR/M026663/1). AJPB and CAM were also supported by the Wellcome Trust (088858; 097377), and by the MRC Centre for Medical Mycology and the University of Aberdeen (MR/N006364/1).Peer reviewedPublisher PD

Solitons with Cubic and Quintic Nonlinearities Modulated in Space and Time

This work deals with soliton solutions of the nonlinear Schroedinger equation with cubic and quintic nonlinearities. We extend the procedure put forward in a recent Letter and we solve the equation in the presence of linear background, and cubic and quintic interactions which are modulated in space and time. As a result, we show how a simple parameter can be used to generate brightlike or darklike localized nonlinear waves which oscillate in several distinct ways, driven by the space and time dependence of the parameters that control the trapping potential, and the cubic and quintic nonlinearities.Comment: 4 pages, 6 figures; version to appear in PRE, R

A Formalization of the Theorem of Existence of First-Order Most General Unifiers

This work presents a formalization of the theorem of existence of most general unifiers in first-order signatures in the higher-order proof assistant PVS. The distinguishing feature of this formalization is that it remains close to the textbook proofs that are based on proving the correctness of the well-known Robinson's first-order unification algorithm. The formalization was applied inside a PVS development for term rewriting systems that provides a complete formalization of the Knuth-Bendix Critical Pair theorem, among other relevant theorems of the theory of rewriting. In addition, the formalization methodology has been proved of practical use in order to verify the correctness of unification algorithms in the style of the original Robinson's unification algorithm.Comment: In Proceedings LSFA 2011, arXiv:1203.542

Extracytoplasmic function (ECF) sigma factor ^F is involved in Caulobacter crescentus response to heavy metal stress

Background: The -proteobacterium Caulobacter crescentus inhabits low-nutrient environments and can tolerate certain levels of heavy metals in these sites. It has been reported that C. crescentus responds to exposure to various heavy metals by altering the expression of a large number of genes.Results: In this work, we show that the ECF sigma factor F is one of the regulatory proteins involved in the control of the transcriptional response to chromium and cadmium. Microarray experiments indicate that F controls eight genes during chromium stress, most of which were previously described as induced by heavy metals. Surprisingly, F itself is not strongly auto-regulated under metal stress conditions. Interestingly, F-dependent genes are not induced in the presence of agents that generate reactive oxygen species. Promoter analyses revealed that a conserved F-dependent sequence is located upstream of all genes of the F regulon. In addition, we show that the second gene in the sigF operon acts as a negative regulator of F function, and the encoded protein has been named NrsF (Negative regulator of sigma F). Substitution of two conserved cysteine residues (C131 and C181) in NrsF affects its ability to maintain the expression of F-dependent genes at basal levels. Furthermore, we show that F is released into the cytoplasm during chromium stress and in cells carrying point mutations in both conserved cysteines of the protein NrsF.Conclusion: A possible mechanism for induction of the F-dependent genes by chromium and cadmium is the inactivation of the putative anti-sigma factor NrsF, leading to the release of F to bind RNA polymerase core and drive transcription of its regulon.</p

Inhibition of neointimal hyperplasia in a sheep model of dialysis access failure with the bioabsorbable Vascular Wrap⁎⁎Vascular Wrap is a trademark of Angiotech Pharmaceuticals, Inc. paclitaxel-eluting mesh

ObjectiveThis study evaluated the effect of a bioabsorbable mesh containing paclitaxel on neointimal hyperplasia in a sheep model of dialysis access failure.MethodsForty neutered male sheep were randomized to one of five parallel groups: no mesh; or a 3-cm × 6-cm mesh with 0.0, 0.3, 0.7, or 1.2 μg/mm2 of paclitaxel for a total dose of 0.0, 0.6, 1.3, or 2.2 mg, respectively. Commercially available 6-mm internal diameter expanded polytetrafluoroethylene grafts were surgically placed between the left common carotid artery and the right external jugular vein. For those animals randomized to one of the mesh groups, the mesh was placed around the distal end of the graft and venous anastomosis. Patency was assessed at weekly intervals throughout the study. Animals were euthanized 8 weeks after implantation, and grafts and veins were harvested. After histologic processing, six cross sections were cut at the venous end of the graft and vessel. The primary and secondary efficacy outcome measures, respectively, were the area and capillary density of the neointima at the graft-vein anastomosis. Histologic analyses were also performed to investigate the effects of the paclitaxel-eluting mesh on the anastomotic site.ResultsGrafts occluded before the scheduled sacrifice in five animals, and they were excluded from the study and not replaced. Control animals developed significant neointimal hyperplasia at the cross section taken perpendicular to the graft at its most distal end: the neointimal area measured 10.5 ± 6.8 mm2 in the no mesh group and 6.4 ± 3.2 mm2 in the zero-dose mesh group (P = .28). In contrast, neointimal area was significantly reduced in the paclitaxel mesh groups: 0.9 ± 1.4 mm2 in the 0.3 μg/mm2 group (P = .008 vs zero-dose mesh), 1.3 ± 1.5 mm2 in the 0.7 μg/mm2 group (P = .004 vs zero-dose mesh), and 1.2 ± 1.4 mm2 in the 1.2 μg/mm2 group (P = .008 vs zero-dose mesh). Capillary density in the neointima at the graft-vein anastomosis decreased with paclitaxel and was significantly reduced in the paclitaxel mesh groups with 0.3 and 1.2 μg/mm2 compared with the zero-dose mesh control (3.6 ± 2.9 vs 8.9 ± 5.6 per mm2 [P = .022] and 1.1 ± 1.7 vs 8.9 ± 5.6 per mm2 [P = .001] respectively). The paclitaxel mesh had no significant effect on healing of the anastomosis or on the thickness of the adjacent vein.ConclusionsIn this model, the paclitaxel-eluting mesh significantly reduced neointimal hyperplasia and neointimal capillary density without apparent toxicity to the adjacent vein.Clinical RelevanceAlthough synthetic grafts (most commonly expanded polytetrafluoroethylene) are currently used in approximately 40% of hemodialysis patients who require a permanent vascular access, primary patency rates remain poor. Most graft failures are caused by venous neointimal hyperplasia, and there are no proven pharmacologic interventions that effectively prevent it. This study provides evidence of the safety and efficacy of a bioabsorbable paclitaxel-eluting mesh for inhibition of neointimal hyperplasia in a sheep model of dialysis access graft failure

Trypanosoma cruzi Infection in Non-Human Primates

For decades, non-human primates (NHPs) have been employed as experimental models to study many aspects of human diseases. They are the closest genetically to humans of any of the models applied in biomedical research; therefore, many authors have published scientific work regarding these animals and infectious diseases, including tuberculosis, AIDS, and tropical diseases. Among these, Chagas disease has caught the attention of many researchers all over the world. Recent studies have demonstrated great similarities with the human pathology, including cardiomyopathy and exacerbated pro-inflammatory response. Besides being genetically close to humans, NHP have a great probability to be naturally infected by Trypanosoma cruzi, which turns them into more interesting models to study Chagas disease mechanisms