Experimental investigation of flow-induced vibration on isolated and tandem circular cylinders fitted with strakes

The effect of varying the geometric parameters of helical strakes on vortex-induced vibration (VIV) is investigated in this paper. The degree of oscillation attenuation or even suppression is analysed for isolated circular cylinder cases. How a cylinder fitted with strakes behaves when immersed in the wake of another cylinder in tandem arrangement is also investigated and these results are compared to those with a single straked cylinder. The experimental tests are conducted at a circulating water channel facility and the cylindrical models are mounted on a low-damping air bearing elastic base with one degree-of-freedom, restricted to oscillate in the transverse direction to the channel flow. Three strake pitches (p) and heights (h) are tested: p = 5, 10, 15d, and h = 0.1, 0.2, 0.25d. The mass ratio is 1.8 for all models. The Reynolds number range is from 1000 to 10000, and the reduced velocity varies up to 21. The cases with h = 0.1d strakes reduce the amplitude response when compared to the isolated plain cylinder, however the oscillation still persists. On the other hand, the cases with h = 0.2, 0.25d strakes almost completely suppress VIV. Spanwise vorticity fields, obtained through stereoscopic digital particle image velocimetry (SDPIV), show an alternating vortex wake for the p = 10d and h = 0.1d straked cylinder. The p = 10d and h = 0.2d cylinder wake has separated shear layers with constant width and no roll-up close to the body. The strakes do not increase the magnitude of the out-of-plane velocity compared to the isolated plain cylinder. However, they deflect the flow in the out-of-plane direction in a controlled way, which can prevent the vortex shedding correlation along the span. In order to investigate the wake interference effect on the strake efficiency, an experimental arrangement with two cylinders in tandem is employed. The centre-to-centre distance for the tandem arrangement varies from 2 to 6. When the downstream p = 10d and h = 0.2d cylinder is immersed in the wake of an upstream fixed plain cylinder, it loses its effectiveness compared with the isolated case. Although the oscillations have significant amplitude, they are limited, which is a different behaviour from that of a tandem configuration with two plain cylinders. For this particular case, the amplitude response monotonically increases for all gaps, except one, a trait usually found in galloping-like oscillations. SDPIV results for the tandem arrangements show alternating vortex shedding and oscillatory wake. (C) 2010 Elsevier Ltd. All rights reserved.

Diversidade genética e resistência natural ao Maraviroc em estirpes do vírus da imunodeficiência humana Tipo 1 (HIV-1) em circulação em utilizadores de drogas por via endovenosa na Grande Lisboa

RESUMO: O maraviroc (MVC) é o único anti-retroviral antagonista do co-receptor CCR5 licenciado e interage com as ansas transmembranares de CCR5, induzindo uma alteração da sua conformação e impedindo a interacção com gp120. O MVC é activo apenas contra estirpes R5 de HIV-1, sendo utilizado em terapia de recurso. Neste trabalho, foi estudada a diversidade genética da região C2V3C3 do gene env de estirpes de HIV-1 de oxicodependentes por via endovenosa da Grande Lisboa, pesquisando-se também a presença de polimorfismos genéticos naturais. Foram utilizadas 52 amostras de plasma e para 35 destas foi amplificado por RT-nested PCR um produto de 565 pb. A análise filogenética revelou a seguinte distribuição de genótipos: 23 B (incluindo, provavelmente, 2 CRF14_BG), 8 A, 3 G e 1 F1. Após tradução, e por comparação com a sequência consenso B, verificou-se uma elevada frequência de polimorfismos genéticos, sendo encontradas algumas “assinaturas de aminoácidos” relativas aos subtipos não-B. Realizou-se ainda uma pesquisa de locais de N-glicosilação e a previsão da utilização de co-receptores (abordagem genotípica), com recurso às regras 11/25 e da carga líquida da ansa V3 e aos programas PSSM e geno2pheno[coreceptor]. Observou-se uma conservação genérica do número de locais de N-glicosilação e foram identificadas 5 sequências com tropismo X4 ou duplo. Por fim, com base na literatura, realizou-se uma pesquisa de polimorfismos genéticos associados a resistência ao MVC presentes na ansa V3. Foi observado um número elevado destas mutações. A presença dos padrões 11S+26V e 20F+25D+26V, num total de 3 sequências, é relevante, visto estes estarem inequivocamente associados à resistência in vivo ao MVC. Apesar de não estar ainda definido um perfil de resistência para o MVC, a presença das mutações encontradas, em indivíduos sem contacto prévio com o fármaco, trará implicações relevantes na sua gestão clínica, considerando a introdução do MVC na terapia de recurso.---------- ABSTRACT: Maraviroc (MVC) is the only CCR5 inhibitor licensed today. This drug interacts with the transmembrane helices of CCR5 co-receptor, inducing a conformation change of its extracellular loops and preventing the interaction with gp120. MVC is only active against R5 strains of HIV-1 and is currently used in salvage therapy. The genetic diversity of the env C2V3C3 region of HIV-1 strains from injecting drug users in the Greater Lisbon was studied, along with the presence of natural genetic polymorphisms. 52 plasma samples were used and the amplification by RT-nested PCR of a 565 bp-product was possible in 35 of them. The phylogenetic analysis revealed 23 sequences classified as subtype B (probably including 2 CRF14_BG), 8 A, 3 G and 1 F1. After translation, the presence of natural genetic polymorphisms was studied by comparison to a subtype B consensus. A high frequency of genetic polymorphisms was observed and significant “amino acid signatures” were found in association with non-B subtypes. A full characterization of the N-glycosylation sites was also performed and a coreceptor prediction (genotypic approach) was accomplished using the 11/25 and the V3 net charge rules and the programs PSSM and geno2pheno[coreceptor]. The number of N-glycosylation sites was generically preserved. Five sequences were defined as X4 or dual-tropic. Based on published data, a search for genetic polymorphisms, present in V3loop, associated to MVC resistance was finally undertaken. Several of such mutations were observed, being particularly interesting the presence of the patterns 11S+26V and 20F+25D+26V, in a total of 3 sequences, since these patterns have unequivocally been associated with MVC resistance in vivo. Although a resistance profile for MVC is not yet defined, the presence of these mutations in MVC-naïve populations may have significant impact in their clinical management in the future, especially considering the introduction of this drug in salvage therapy.

Changes in peripheral refractive profile after orthokeratology for different degrees of myopia

Purpose: The purpose of this study was to evaluate the effect of orthokeratology for different degrees of myopia correction in the relative location of tangential (FT) and sagittal (FS) power errors across the central 70 of the visual field in the horizontal meridian. Methods: Thirty-four right eyes of 34 patients with a mean age of 25.2 ± 6.4 years were fitted with Paragon CRT (Mesa, AZ) rigid gas permeable contact lenses to treat myopia (2.15 ± 1.26D, range: 0.88 to 5.25D). Axial and peripheral refraction were measured along the central 70 of the horizontal visual field with the Grand Seiko WAM5500 open-field auto-refractor. Spherical equivalent (M), as well as tangential (FT) and sagittal power errors (FS) were obtained. Analysis was stratified in three groups according to baseline spherical equivalent: Group 1 [MBaseline = 0.88 to 1.50D; n = 11], Group 2 [MBaseline = 1.51 to 2.49D; n = 11], and Group 3 [MBaseline = 2.50 to 5.25D; n = 12]. Results: Spherical equivalent was significantly more myopic after treatment beyond the central 40 of the visual field (p50.001). FT became significantly more myopic for all groups in the nasal and temporal retina with 25 (p 0.017), 30 (p 0.007) and 35 (p 0.004) of eye rotation. Myopic change in FS was less consistent, achieving only statistical significance for all groups at 35 in the nasal and temporal retina (p 0.045). Conclusions: Orthokeratology changes significantly FT in the myopic direction beyond the central 40 of the visual field for all degrees of myopia. Changes induced by orthokeratology in relative peripheral M, FT and FS with 35 of eye rotation were significantly correlated with axial myopia at baseline. Keywords: Field

Análise da prevalência da miopia em estudantes universitários

Dissertação de mestrado em Optometria Avançada

The Effect Of Induced Intraocular Straylight (cataract Simulation) On Sensitivity Measures Of Standard Automated Perimetry, Pulsar Perimetry And Moorfields Motion Displacement Test

Purpose: To investigate the effect of incremental increases in intraocular straylight on threshold measurements made by three modern forms of perimetry: Standard Automated Perimetry (SAP) using Octopus (Dynamic, G-Pattern), Pulsar Perimetry (PP) (TOP, 66 points) and the Moorfields Motion Displacement Test (MDT) (WEBS, 32 points).Methods: Four healthy young observers were recruited (mean age 26yrs [25yrs, 28yrs]), refractive correction [+2 D, -4.25D]). Five white opacity filters (WOF), each scattering light by different amounts were used to create incremental increases in intraocular straylight (IS). Resultant IS values were measured with each WOF and at baseline (no WOF) for each subject using a C-Quant Straylight Meter (Oculus, Wetzlar, Germany). A 25 yr old has an IS value of ~0.85 log(s). An increase of 40% in IS to 1.2log(s) corresponds to the physiological value of a 70yr old. Each WOFs created an increase in IS between 10-150% from baseline, ranging from effects similar to normal aging to those found with considerable cataract. Each subject underwent 6 test sessions over a 2-week period; each session consisted of the 3 perimetric tests using one of the five WOFs and baseline (both instrument and filter were randomised).Results: The reduction in sensitivity from baseline was calculated. A two-way ANOVA on mean change in threshold (where subjects were treated as rows in the block and each increment in fog filters was treated as column) was used to examine the effect of incremental increases in straylight. Both SAP (p<0.001) and Pulsar (p<0.001) were significantly affected by increases in straylight. The MDT (p=0.35) remained comparatively robust to increases in straylight.Conclusions: The Moorfields MDT measurement of threshold is robust to effects of additional straylight as compared to SAP and PP.

[Magnificentiores selectioresque Urbis Venetiarum prospectus quos olim Michael Marieschi, Venetus pictor et architectus in plerisque tabulis depinxit, nunc vero ab ipsomet acurate delineante, incidente, tyspisque mandante, iterum in sexdecim aereis tabulis in lucem aeduntur]. [9], Prospectus Canalis magni Coenobium D: Clarae versus exhibens, ad dextram Templum S: S: Simeonis, et Iudae : [estampe] / Mich.l Marieschi del.t et inci.t

Référence bibliographique : Toledano, Marieschi, 25d

Carfentrazone-ethyl aplicado em pós-emergência para o controle de Ipomea spp. e Commelina benghalensis na cultura da cana-de-açúcar

Este trabalho teve como objetivos determinar a eficácia e seletividade do carfentrazone-ethyl no controle de plantas daninhas na cultura da cana-de-açúcar e avaliar curvas de dose-resposta desse herbicida em Ipomoea spp. e Commelina benghalensis. Desenvolveu-se um ensaio de campo, em pós-emergência das plantas daninhas e da cultura (cv. RB72-454). O delineamento experimental utilizado foi do tipo blocos ao acaso, com os seguintes tratamentos: carfentrazone a 5, 10, 20, 30 e 50 g ha-1 e metribuzin a 2.400 g ha-1. As plantas daninhas que infestavam a área eram Ipomoea nil, I. grandifolia, I. quamoclit, Momordica charantia e C. benghalensis. As avaliações de controle visual e fitotoxicidade foram realizadas aos 15, 30 e 45 dias após a aplicação dos herbicidas. Para elaboração das curvas de dose-resposta, um experimento foi instalado em casa de vegetação, com as plantas daninhas I. nil, I. hederifolia, I. grandifolia, I. quamoclit e C. benghalensis. As doses do herbicida carfentrazone foram: 10D, 4D, 2D, D, 0,5D, 0,25D, 0,125D, 0,1D e 0,01D, em que D = 20 g ha¹. Os dados foram analisados a partir de curvas de dose-resposta de controle visual e massa fresca. No experimento de campo, observou-se excelente controle das plantas daninhas, sendo a dose de 50 g ha-1 de carfentrazone a mais eficiente. Nenhum tratamento causou danos à cana-de-açúcar. O experimento de casa de vegetação permitiu concluir que a ordem decrescente de sensibilidade das espécies de corda-de-viola ao carfentrazone-ethyl é: I. hederifolia > I. quamoclit > I. nil > I. grandifolia; e que C. benghalensis é controlada pelo carfentrazone a partir da dose de 5 g ha-1.

Suscetibilidade comparativa a herbicidas pós-emergentes de biótipos de Digitaria ciliaris resistente e suscetível aos inibidores da ACCase

Esta pesquisa foi conduzida com o objetivo de avaliar a possibilidade de resistência múltipla aos herbicidas inibidores da ACCase, ALS e síntese de carotenos em um biótipo de capim-colchão (Digitaria ciliaris) resistente aos inibidores da ACCase. O experimento foi conduzido em casa de vegetação, utilizando dois biótipos de capim-colchão: um resistente (R) e outro suscetível (S) aos herbicidas inibidores da ACCase. O delineamento experimental utilizado foi o de blocos ao acaso, com quatro repetições. Foram utilizados 11 herbicidas: fluazifop-p-butil, haloxyfop-r-methyl, propaquizafop, sethoxydim, tepraloxydim, clethodim, fenoxaprop + clethodim, imazethapyr, nicosulfuron, iodosulfuron + foramsulfuron e mesotrione. Para cada herbicida, os tratamentos resultaram da combinação fatorial entre os dois biótipos de capim-colchão e 10 doses (0,0D; 0,016D; 0,03D; 0,06D; 0,25D; 0,5D; 1,0D; 2,0D; 4,0D; e 16,0D), em que D é a dose recomendada para cada produto. Os herbicidas foram aplicados sobre as plantas de capim-colchão em estádio de desenvolvimento de 3-4 folhas. Avaliou-se a porcentagem de controle aos 28 dias após a aplicação (DAA). O biótipo R foi confirmado como resistente aos herbicidas inibidores da ACCase (grupos químicos dos ariloxifenoxipropionatos e cicloexanodionas) com níveis variáveis de resistência cruzada. O biótipo R foi controlado satisfatoriamente pela dose de campo de todos os herbicidas alternativos aplicados (sulfoniluréias, imidazolinonas e inibidores da síntese de caroteno), excluindo a hipótese de resistência múltipla nesse biótipo de capim-colchão.

Retinoscopia com luz em faixa em cães fácicos, afácicos e pseudofácicos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biometria ocular na espécie Cebus apella

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Keratometry device for surgical support

Abstract Background High astigmatisms are usually induced during corneal suturing subsequent to tissue transplantation or any other surgery which involves corneal suturing. One of the reasons is that the procedure is intimately dependent on the surgeon's skill for suturing identical stitches. In order to evaluate the influence of the irregularity on suturing for the residual astigmatism, a prototype for ophthalmic surgical support has been developed. The final intention of this prototype is to be an evaluation tool for guided suture and as an outcome diminish the postoperative astigmatism. Methods The system consists of hand held ring with 36 infrared LEDs, that is to be projected onto the lachrymal film of the cornea. The image is reflected back through the optics of the ocular microscope and its distortion from the original circular shape is evaluated by developed software. It provides keratometric and circularity measurements during surgery in order to guide the surgeon for uniformity in suturing. Results The system is able to provide up to 23D of astigmatism (32D - 55D range) and is ± 0.25D accurate. It has been tested in 14 volunteer patients intraoperative and has been compared to a commercial keratometer Nidek Oculus Hand-held corneal topographer. The correlation factors are 0.92 for the astigmatism and 0.97 for the associated axis. Conclusion The system is potentially efficient for guiding the surgeon on uniformity of suturing, presenting preliminary data indicating an important decrease on the residual astigmatism, from an average of 8D - for patients not submitted to the prototype guidance - to 1.4D - for patients who have actually been submitted to the prototype guidance - after the first 24 hours post-surgery and in the subsequent weeks. It also indicates that the surgeon should achieve circularity greater or equal to 98% in order to avoid postoperative astigmatisms over 1D. Trial Registration Trial registration number: CAAE - 0212.0.004.000-09.

Patient-specific finite-element simulation of the human cornea: A clinical validation study on cataract surgery

The planning of refractive surgical interventions is a challenging task. Numerical modeling has been proposed as a solution to support surgical intervention and predict the visual acuity, but validation on patient specific intervention is missing. The purpose of this study was to validate the numerical predictions of the post-operative corneal topography induced by the incisions required for cataract surgery. The corneal topography of 13 patients was assessed preoperatively and postoperatively (1-day and 30-day follow-up) with a Pentacam tomography device. The preoperatively acquired geometric corneal topography – anterior, posterior and pachymetry data – was used to build patient-specific finite element models. For each patient, the effects of the cataract incisions were simulated numerically and the resulting corneal surfaces were compared to the clinical postoperative measurements at one day and at 30-days follow up. Results showed that the model was able to reproduce experimental measurements with an error on the surgically induced sphere of 0.38D one day postoperatively and 0.19D 30 days postoperatively. The standard deviation of the surgically induced cylinder was 0.54D at the first postoperative day and 0.38D 30 days postoperatively. The prediction errors in surface elevation and curvature were below the topography measurement device accuracy of ±5μm and ±0.25D after the 30-day follow-up. The results showed that finite element simulations of corneal biomechanics are able to predict post cataract surgery within topography measurement device accuracy. We can conclude that the numerical simulation can become a valuable tool to plan corneal incisions in cataract surgery and other ophthalmosurgical procedures in order to optimize patients' refractive outcome and visual function.