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Stimulated by a rising interest in the D-Band in research and industry, the demand for accessible measurement equipment is increasing. As the frequency range of vector network analyzers (VNAs) is insufficient, vector network analyzer extension (VNAX) modules are needed. Commercially available options consist of discrete components, which increases the size and price of such modules. Therefore, in this work, we present a VNAX module, which combines most of the functions on a single SiGe-MMIC. To demonstrate its functionality, we compare it to a state-of-the-art VNAX module in a two-port WR 4.3 waveguide measurement. Additionally, we present a maximum system and receiver dynamic range of 75 dB and 129 dB at a resolution bandwidth of 10 Hz. To address potential temperature concerns of our approach, the achieved phase- and magnitude stability is typically in a range of ?0.2 dB and ?1 degree for the time span of one hour.

Objective Inter-ocular asymmetry in anterior corneal high-order aberrations has previously not been investigated. This study aims to investigate the normal range of inter-ocular asymmetry in corneal high-order aberrations (HOAs) using a Placido disk-based corneal topographer to explore the relationship between the HOA parameters of the anterior corneal for each eye individually and the refractive error. Patients and methods A total of 257 subjects (98 males and 159 females) were participated, with an age range of 6 to 81 years (average of 40.2 ±17.53). Participants were divided into three groups: myopia (spherical equivalent (SEQ) of refraction ≥-0.50 D), hypermetropia (SEQ ≥+0.50 D), and emmetropia. For all patients, high-order aberrations were measured using a corneal topographer (CA.200TM; Topcon). Inter-ocular asymmetry was represented by RMS (root mean square) for three, five, and seven mm as pupil entry; aberrations for five mm pupil (vertical and oblique trefoil, vertical and horizontal comma, and primary spherical aberration) were recorded using the instrument's built-in software. Results Hypermetropes exhibit the highest inter-ocular asymmetry of all RMS values, mostly in spherical aberrations, and higher-order trefoil values. Oblique trefoil aberrations had the highest interocular asymmetry in the myopic groups. The interocular asymmetry in horizontal coma values was the highest in emmetropes and the lowest in hypermetropes. Conclusion To our knowledge, this is the first observational study of inter-ocular differences in high-order aberrations of the anterior corneal surface of the human eye. This study's results could be used to establish normal values of inter-ocular asymmetry of HOAs of the anterior cornea. The use of such normal values should be investigated further to serve as a guideline for clinicians when establishing the best management route for the patient's refractive error.

AIM: To evaluate retinal parameters in a sample of healthy young Caucasian adults to define the normal or physiological range of inter-ocular asymmetry in this particular age and ethnic group. METHODS: Study sample consisted of 37 Caucasian children and young adults aged between 12 and 23y (spherical equivalent from -3.00 D to +4.00 D, anisometropia

PURPOSE:: To investigate the normal range of interocular asymmetry in choroidal thickness and retinal sensitivity in high myopia without ocular fundus manifestations and to determine the relationship between interocular asymmetry and refractive error. METHODS:: Forty-three patients (35.07 ± 13.31 years) with high myopia and 45 healthy participants (39.9 ± 14.1 years) were administered an ocular coherence tomography and a microperimetry examination to determine choroidal thickness and retinal sensitivity at the foveal region and at 1, 2, and 3 mm, nasally, temporally, superiorly, and inferiorly. Absolute interocular differences were calculated to determine the normal range of asymmetry, in 95% confidence intervals. RESULTS:: The choroid was thinner in the myopic group at all explored locations (all P < 0.05), with larger absolute interocular differences in most of the choroidal locations under evaluation (all P < 0.05). Similarly, retinal sensitivity was reduced in the myopic group, although statistically significant differences were only encountered at the subfoveal location (P = 0.001). Retinal sensitivity asymmetry was found to increase with refractive error. CONCLUSION:: The expanded range of choroidal thickness and retinal sensitivity asymmetry found in high myopia in the absence of disease is of relevance when exploring these patients for early signs of ocular pathology.

PURPOSE To estimate the association between choroidal thickness in the macular area and retinal sensitivity in eyes with high myopia. METHODS This investigation was a transversal study of patients with high myopia, all of whom had their retinal sensitivity measured with macular integrity assessment microperimetry. The choroidal thicknesses in the macular area were then measured by optical coherence tomography, and statistical correlations between their functionality and the anatomical structuralism, as assessed by both types of measurements, were analyzed. RESULTS Ninety-six eyes from 77 patients with high myopia were studied. The patients had a mean age ± standard deviation of 38.9 ± 13.2 years, with spherical equivalent values ranging from -6.00 diopter to -20.00 diopter (8.74 ± 2.73 diopter). The mean central choroidal thickness was 159.00 ± 50.57. The mean choroidal thickness was directly correlated with sensitivity (r = 0.306; P = 0.004) and visual acuity but indirectly correlated with the spherical equivalent values and patient age. The mean sensitivity was not significantly correlated with the macular foveal thickness (r = -0.174; P = 0.101) or with the overall macular thickness (r = 0.103; P = 0.334); furthermore, the mean sensitivity was significantly correlated with visual acuity (r = 0.431; P < 0.001) and the spherical equivalent values (r = -0.306; P = 0.003). CONCLUSION Retinal sensitivity in highly myopic eyes is directly correlated with choroidal thickness and does not seem to be associated with retinal thickness. Thus, in patients with high myopia, accurate measurements of choroidal thickness may provide more accurate information about this pathologic condition because choroidal thickness correlates to a greater degree with the functional parameters, patient age, and spherical equivalent values.

A crack in structural member introduces local flexibility which is function of crack depth and location. This flexibility changes the dynamic behavior of the system and its stability characteristics. A continuous cracked beam vibration theory is implemented for the lateral vibration of cracked Euler–Bernoulli beams with single-edge open cracks. In this work, the crack identification as on line health monitoring for simply supported graphite/epoxy fiber reinforced composite beams is considered. The effects of crack depth and location, fiber orientation, and fiber volume fraction on the flexibility and consequently on natural frequency and mode shapes for cracked fiber reinforced composite beams are investigated.Copyright © 2010 by ASME