Measurement and testing problems experienced during FAA's emissions testing of general aviation piston engines

The importance of measuring accurate air and fuel flows as well as the importance of obtaining accurate exhaust pollutant measurements were emphasized. Some of the problems and the corrective actions taken to incorporate fixes and/or modifications were identified

A fourth spatial dimension for the Universe

The contemporary physical theories are based on several fundamental physical constants. No theoretical framework provides their experimental values. Here, we might have found two formulas yielding the value of the Planck constant and the speed of gravitational waves according to the vacuum properties. In particular, they highly suggest that gravitational waves actually travel in matter. Because there is no dense matter between high-mass bodies in the Universe, the relations would mean that the structure of the Universe is at least pentadimensional (four spatial and one temporal dimensions). We then discuss the implications of this feature on contemporary physics

Presenting features of primary angle-closure glaucoma in patients of mixed ethnic background

The relative frequency with which patients present with acute or chronic angle-closure glaucoma depends on their ethnic background. In order to examine the presenting features and effects of primary angle-closure glaucoma in people of mixed ethnicity, we reviewed all 'coloured' patients who presented to Groote Schuur Hospital with this diagnosis during a 5-year period. Of the 92 patients, 33 (36%) presented with acute angle-closure glaucoma and 59 (64%) with chronic angleclosure glaucoma. The level of intra-ocular pressure on presentation correlated well with the number of quadrants of angle closure (correlation coefficient: r =0,73, P < 0,001). When individual eyes were assessed, a mean cup/disc ratio of ≥ 0,8 was present in 350 /0 (65/184) and glaucomatous visual field loss was present in 56,5% (104/184). Total uni-ocular blindness secondary to chronic angle-closure glaucoma, was found in 16 (17%) patients. This study indicates that 'coloured' patients with primary angle-closure glaucoma are more likely to present with chronic symptoms and signs, and that the disease may result in devastating ocular damage and visual loss. In patients of mixed ethnic background with signs of primary glaucoma, chronic angle-closure should be excluded by careful gonioscopic evaluation of the drainage structures of the eye

Malignant Glaucoma: A Review of the Modern Literature

Malignant glaucoma is a rare form of glaucoma that typically follows surgery in patients with primary angle closure and primary angle-closure glaucoma. In this paper, the clinical features, classification, pathogenesis, and principles of management are discussed. Despite a high prevalence of primary angle closure glaucoma in South-East Asia, the vast majority of cases of malignant glaucoma are reported in White populations. This may reflect differing mechanisms of angle closure in White and Asian patients, which somehow reduces the likelihood of an aberrant relationship developing between the lens, ciliary body, anterior hyaloid, and vitreous structures within the eye. Although the exact underlying pathogenic mechanism remains unclear, the prognosis is good with modern medical, laser, and surgical treatment modalities

Iridoschisis and keratoconus in a patient with severe allergic eye disease and compulsive eye rubbing: a case report

Background Iridoschisis is a rare disorder characterized by splitting of the anterior and posterior iris stroma, resulting in disintegrated iris fibrils which float freely in the anterior chamber. We report an exceptional case of bilateral iridoschisis occurring in conjunction with keratoconus and severe allergic eye disease. Case Presentation A 24-year-old white man had had periocular contact dermatitis and allergic eye disease from the age of 3 years. He was allergic to grass, animal hair, and pollen and worked grooming horses. He compulsively rubbed his eyes. There was no history of previous blunt trauma to either eye. There were signs of bilateral iridoschisis and keratoconus with allergic conjunctivitis, all of which were more severe in his right eye. An open drainage angle was identified bilaterally on gonioscopy, excluding primary angle closure. There was no evidence of glaucoma in either eye. Conclusions There are two previous cases reporting the combination of iridoschisis and keratoconus, but no clear common etiology has been identified. In this case there was no evidence of angle closure but there were signs of allergic conjunctivitis. This amalgamation of signs might be explained on the basis of habitual eye rubbing. Treating the allergic eye disease has attenuated this behavior.</p

Velocity profiles in shear-banding wormlike micelles

Using Dynamic Light Scattering in heterodyne mode, we measure velocity profiles in a much studied system of wormlike micelles (CPCl/NaSal) known to exhibit both shear-banding and stress plateau behavior. Our data provide evidence for the simplest shear-banding scenario, according to which the effective viscosity drop in the system is due to the nucleation and growth of a highly sheared band in the gap, whose thickness linearly increases with the imposed shear rate. We discuss various details of the velocity profiles in all the regions of the flow curve and emphasize on the complex, non-Newtonian nature of the flow in the highly sheared band.Comment: 4 pages, 5 figures, submitted to Phys. Rev. Let

Shear-banding in a lyotropic lamellar phase, Part 2: Temporal fluctuations

We analyze the temporal fluctuations of the flow field associated to a shear-induced transition in a lyotropic lamellar phase: the layering transition of the onion texture. In the first part of this work [Salmon et al., submitted to Phys. Rev. E], we have evidenced banded flows at the onset of this shear-induced transition which are well accounted for by the classical picture of shear-banding. In the present paper, we focus on the temporal fluctuations of the flow field recorded in the coexistence domain. These striking dynamics are very slow (100--1000s) and cannot be due to external mechanical noise. Using velocimetry coupled to structural measurements, we show that these fluctuations are due to a motion of the interface separating the two differently sheared bands. Such a motion seems to be governed by the fluctuations of $\sigma^\star$, the local stress at the interface between the two bands. Our results thus provide more evidence for the relevance of the classical mechanical approach of shear-banding even if the mechanism leading to the fluctuations of $\sigma^\star$ remains unclear

Energetics, skeletal dynamics and long-term predictions in Kolmogorov-Lorenz systems

We study a particular return map for a class of low dimensional chaotic models called Kolmogorov Lorenz systems, which received an elegant general Hamiltonian description and includes also the famous Lorenz63 case, from the viewpoint of energy and Casimir balance. In particular it is considered in detail a subclass of these models, precisely those obtained from the Lorenz63 by a small perturbation on the standard parameters, which includes for example the forced Lorenz case in Ref.[6]. The paper is divided into two parts. In the first part the extremes of the mentioned state functions are considered, which define an invariant manifold, used to construct an appropriate Poincare surface for our return map. From the experimental observation of the simple orbital motion around the two unstable fixed points, together with the circumstance that these orbits are classified by their energy or Casimir maximum, we construct a conceptually simple skeletal dynamics valid within our sub class, reproducing quite well the Lorenz map for Casimir. This energetic approach sheds some light on the physical mechanism underlying regime transitions. The second part of the paper is devoted to the investigation of a new type of maximum energy based long term predictions, by which the knowledge of a particular maximum energy shell amounts to the knowledge of the future (qualitative) behaviour of the system. It is shown that, in this respect, a local analysis of predictability is not appropriate for a complete characterization of this behaviour. A perspective on the possible extensions of this type of predictability analysis to more realistic cases in (geo)fluid dynamics is discussed at the end of the paper.Comment: 21 pages, 14 figure

Trisomy 19 ependymoma, a newly recognized genetico-histological association, including clear cell ependymoma

Ependymal tumors constitute a clinicopathologically heterogeneous group of brain tumors. They vary in regard to their age at first symptom, localization, morphology and prognosis. Genetic data also suggests heterogeneity. We define a newly recognized subset of ependymal tumors, the trisomy 19 ependymoma. Histologically, they are compact lesions characterized by a rich branched capillary network amongst which tumoral cells are regularly distributed. When containing clear cells they are called clear cell ependymoma. Most trisomy 19 ependymomas are supratentorial WHO grade III tumors of the young. Genetically, they are associated with trisomy 19, and frequently with a deletion of 13q21.31-31.2, three copies of 11q13.3-13.4, and/or deletions on chromosome 9. These altered chromosomal regions are indicative of genes and pathways involved in trisomy 19 ependymoma tumorigenesis. Recognition of this genetico-histological entity allows better understanding and dissection of ependymal tumors