Oval Elements Research Articles

Assessment of a Clinical Test for Detection of Alteration in Visual Perception Due to Astigmatism.

Astigmatism blurs the retinal image of a circular spot along a particular orientation rendering it an elliptical shape. Astigmatic patients demonstrate adaptation to residual astigmatic blur that may affect their discrimination between oval and circular targets. The Wilkins Egg and Ball Test (WEBT) was created to detect altered visual perception due to residual astigmatic blur by discriminating a circle within a row of oval elements. This prospective, cross-sectional study examined the utility of WEBT in detecting uncorrected residual astigmatism on the perception of form symmetry in astigmatic and keratoconic participants as well as normal participants with induced astigmatism at four primary meridians. The mean search time (sT) and number of errors (noE) of 33 non-astigmatic controls (mean age: 24±5, range: 18-43, 6 males), 23 astigmatic participants (mean age: 36±12, range: 18-43, 6 males) and 13 keratoconic participants (N=22 eyes, mean age: 36±12, range: 18-58, 6 males) were measured under baseline, and 2.00 DC induced cylinder at four primary meridians, and for uncorrected, spherical-correction only, and fully corrected conditions, respectively. Mean sT and noE were converted to Z-scores, combined for each condition, and compared using repeated measures ANOVA with post-hoc analysis. Combined Z-scores for the controls were significantly worse (p<0.001) for all induced cylinder conditions. The induced 180° condition was significantly better than 45° and 90° conditions (p=0.04), but not the 135° condition. For both astigmatic and keratoconic cohorts, Z-scores of the uncorrected condition were significantly worse than the fully corrected condition (both p<0.01), but the fully corrected and spherical-only conditions did not differ significantly (p=0.06 and p=0.05, respectively). In accommodating young adults, WEBT detected altered visual perception due to overall blur, and moderate-high amounts of uncorrected induced astigmatism and keratoconus, but is not useful as a tool for detection of altered visual perception due to small residual astigmatic blur.

Evaluating and forecasting movement patterns of magnetically driven microbeads in complex geometries

The manipulation of superparamagnetic microbeads for lab-on-a-chip applications relies on the steering of microbeads across an altering stray field landscape on top of soft magnetic parent structures. Using ab initio principles, we show three-dimensional simulations forecasting the controlled movement of microbeads. Simulated aspects of microbead behaviour include the looping and lifting of microbeads around a magnetic circular structure, the flexible bead movement along symmetrically distributed triangular structures, and the dragging of magnetic beads across an array of exchange biased magnetic microstripes. The unidirectional motion of microbeads across a string of oval elements is predicted by simulations and validated experimentally. Each of the simulations matches the experimental results, proving the robustness and accuracy of the applied numerical method. The computer experiments provide details on the particle motion not accessible by experiments. The simulation capabilities prove to be an essential part for the estimation of future lab-on-chip designs.

New Developments in Understanding the Histological Structure of Human Ear Cartilage

Histological, immunohistochemical and molecular examination of bioptic samples of 30 normal adult auricular cartilages and small samples from 6 ear cartilages from aborted foetuses was performed. The adult cartilage was the tissue with minimal proliferative activity, which we were able to confirm with antibodies against Ki67 in contrast to a high proliferative activity in the auricular cartilage of foetal tissues. It may therefore be presumed that the process of foetal tissue maturation is undoubtedly associated with a significant reduction in proliferative activity. The mature lamella of the adult auricular cartilage has a histological tri-lamellar structure. There are a great number of elastic fibres in the intercellular matrix of the central zone, which are conversely present in only small amounts in both peripheral layers. While the external layer of the concave surface of the cartilage contains a fewer number of oval elements, the external layer of the convex side is composed of numerous fusiform chondrocytes. Antibodies against various subtypes of S-100 protein showed that auricular chondrocyte activity is modified depending on the configuration of individual distinct zones (isoforms A1, A6, B2 and P were positive in all layers, isoforms A2 and A2 in peripheral zones). The most active cells metabolically are most likely chondrocytes in both external layers adjacent to the perichondrium. We have also demonstrated α-smooth muscle actin (SMA)-positive chondrocytes in both peripheral layers of the auricular cartilage adjacent to the perichondrium. In addition, we found definite differences in the distribution of actin-positive cells depending on the external shape of the pinna. The majority of these fusiform cells were localised primarily in the areas of great curvature of the pinna, especially the convex side, as mentioned above. On the basis of these unique structural features we assume that the ear cartilage may embody an example of the socalled intelligent biological material, which has its internal structure made in such a way as to more easily develop and yet still maintain all the shape characteristics of the human auricle. The knowledge of these specific structural characteristics is important especially for use of auricular cartilage in auricular reconstruction.

Lazika Pier Sculpture

AbstractLazika is a new city in Georgia located on the Black Sea coast. The one‐hundred meter long Lazika Pier with its 31 m high landmark sculpture is one of the first structures to mark the beginning of the development of this new metropolis.The sculpture designed by German architect Jürgen Mayer H. consists of stacked oval elements – so called blobs – organized in seven levels. The blobs are subdivided into vertical plain levels running in an orthogonal direction with a distance of 90 cm. Due to the exposed position, tough requirements concerning corrosion resistance and a pretty tight timetable for design, fabrication and erection, structural steel has been chosen as the building material. The sculpture consists of steel plates with varying thicknesses of 5 to 10 mm. Elements composed of plasma‐cut plates were pre‐fabricated within a site workshop and installed using mobile cranes. Exterior and interior lighting features provide a dynamic and pulsating look to the sculpture.

Giemsa and Grocott in the recognition of Histoplasma capsulatum in blood smears

ObjectiveTo facilitate the recognition of intracellular yeasts of Histoplasma capsulatum and differentiate it from Leishmania amastigotes and other parasites, using the combination of Giemsa and a rapid modification of Grocott stains to peripheral blood smears in a hematological study. MethodsThe combination of both stains was applied consecutively (first Grocott and then Giemsa) to previously fixed peripheral blood smears. Microscopy was performed with 400× and 1 000×, the latter using immersion oil. ResultsThe yeasts of Histoplasma capsulatum were observed into the cytoplasm of leukocytes as brownish oval elements, with 3–4 μm in diameter. ConclusionsThe combination of both techniques is a simple and fast method to facilitate recognition of intracellular yeasts and it is different from intracellular parasitic elements. Moreover, it allows distinguishing the cell elements that are in the microscopic preparations. It may be very helpful in those cases in which the presumptive diagnosis of histoplasmosis has not been established yet and where other more sophisticated methods are not available.

Ultrahigh-Field 7-T Magnetic Resonance Carotid Vessel Wall Imaging

Magnetic resonance imaging (MRI) of the vessel wall enables determination of luminal area, vessel wall thickness, and atherosclerotic plaque characteristics. For clinical application, high spatial resolution, derived from optimal signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), is paramount. Vessel wall MRI is expected to benefit from higher magnetic field strength. Therefore, the purposes of the present study were to develop an ultrahigh-field 7-T MRI hardware and protocols for vessel wall imaging of the carotid artery and to compare quantitative parameters of vessel wall morphology and image quality between 3-T and 7-T MRI. Eighteen volunteers (11 men and 7 women; mean [SD] age, 29 [7] years) underwent MRI examinations at 7 T (using a custom-built surface transmit/receive coil of 15-cm diameter) and at 3 T (using a commercial phased-array coil with 2 flexible oval elements, 14 × 17 cm each). Magnetic resonance imaging of the left common carotid artery vessel wall was performed at 7 T with identical in-plane resolution as that of 3-T MRI (0.46 × 0.46 mm), providing transverse T1- and T2-weighted images. Blinded analysis of morphologic measurements (luminal area and vessel wall area), SNR for vessel wall (SNRVW), and the CNR between the lumen and the vessel wall were compared between 7 and 3 T. Morphologic carotid vessel wall measurements were comparable between 7 and 3 T for both T1-weighted images (luminal area: intraclass correlation [ICC], 0.81 and vessel wall area: ICC, 0.84) and T2-weighted images (luminal area: ICC, 0.97 and vessel wall area: ICC, 0.92). At 7 T, SNRVW and CNR were significantly higher compared with 3-T MRI for both T1- (P < 0.001) and T2-weighted images (P < 0.05), with gain factors ranging from 1.3 to 3.6. Ultrahigh-field 7-T MR carotid vessel wall imaging is feasible. 7-T MRI of the common carotid artery has comparable accuracy for determining luminal area and vessel wall area and has improved SNRVW and CNR compared with 3-T MRI. Therefore, ultrahigh-field 7-T vessel wall MRI may enable a more detailed assessment of plaque morphology.

Aseismic Roof Isolation System Built with Steel Oval Elements: Exploratory Study

Presented herein are the details of and results from an experimental study conducted to assess the feasibility and effectiveness of a proposed roof isolation system whose purpose is to reduce earthquake damage in buildings. The proposed isolation system entails the detachment of a building's roof from the rest of the building through the insertion of sliding bearings and the attachment of oval-shaped steel elements between the building's roof and the structure below. The objective is to form a simple resonant oscillator with a building's roof and these oval elements, with the roof providing the mass of the oscillator and the oval elements its spring and damper. An additional intention is to make the steel oval elements undergo a large number of inelastic deformation cycles and dissipate, as a result, a large portion of the energy transmitted to a building during an earthquake. The study involves the testing of a small steel frame on a shaking table alternatively with and without the proposed roof isolation system and a comparison of the story drifts and floor accelerations attained in each case. In the conducted tests, the suggested isolation technique effectively reduces the seismic response of the frame. It is concluded, thus, that the proposed roof isolation system has the potential for the development of an inexpensive and effective way to reduce earthquake damage in some buildings and merits further study.