Diagnostic methods for dysthyroid optic neuropathy: A systematic review and analysis.

Diagnosis of dysthyroid optic neuropathy (DON) typically relies on a set of diagnostic clinical features, including decreased visual acuity, impaired color vision, presence of relative afferent pupillary defect, optic disc swelling and ancillary tests including visual field (VF), pattern visual evoked potential (pVEP), and apical crowding or optic nerve stretching on neuroimaging. We summarize various diagnostic methods to establish or rule out DON. A total of 95 studies (involving 4619 DON eyes) met the inclusion criteria. All of the studies considered clinical features as evidence of DON, while most of the studies confirmed DON diagnosis by combining clinical features with ancillary tests. Forty studies (42.1%) used at least 2 out of the 3 tests (VF, pVEP and neuroimaging) and 13 studies (13.7%) used all 3 tests to diagnose DON. In 64 % of the published studies regarding DON, the diagnostic methods of DON were not specified. It is important to note the limitations of relying solely on clinical features for diagnosing DON. On the other hand, since some eyes with optic neuropathy can be normal in one ancillary test, but abnormal in another, using more than one ancillary test to aid diagnosis is crucial and should be interpreted in correlation with clinical features. We found that the diagnostic methods of DON in most studies involved using a combination of specific clinical features and at least 2 ancillary tests.

Model-based autonomous plate defects visualization method for quantitative wall-thinning estimation.

The visualization of the wall thinning of plate-like structures using scanning laser Doppler vibrometry (SLDV) is a promising method in nondestructive evaluation using laser ultrasonics. In particular, the Lamb-wave-based SLDV method that uses continuous excitation exhibits excellent performance for the estimation of the wall thinning of plates. Currently, plate thickness is quantitatively evaluated based on wavenumber analysis using measured signals. However, it is difficult to estimate plate thickness automatically below the product of frequency and thickness of 6 MHz·mm without knowing the wavenumber sensitivity and minimum wavenumber distance from reference mode owing to the lack of the physical understanding of Lamb waves. In this study, a model-based autonomous plate defects visualization method is proposed for the quantitative imaging of the wall thinning of plates so that inspectors can use scanning laser Doppler vibrometry (SLDV) without any knowledge of Lamb waves and its signal processing. Interdigital-transducer-based SLDV is utilized to validate the proposed method, and a 6-mm-thick carbon steel plate with 1-8% wall thinning, and a 2-mm-thick aluminum plate with Y-shaped wall thinning are used. Experiments demonstrate that the capability of the proposed method for detecting wall thinning in plates is equivalent to that of manual plate defects visualization method.

Field-deployable measurement technique for absolute acoustic nonlinearity parameter values.

Over the past two decades, several researchers have demonstrated that changes in the acoustic nonlinearity parameter ß can be related to changes in material properties due to mechanical and/or thermal degradation processes. Generally, a piezoelectric sensor-based detection method is used to measure changes in ß values because it is operationally simpler than the complex capacitive detection method. However, this method is limited to measuring only relative changes in ß values; whereas, the absolute ß values of components in service often need to be measured in the field to quantify the degradation level. Accordingly, a novel field-deployable method for measuring absolute ß values was developed in this study. Nonlinear ultrasonic experiments were conducted using capacitive detection, conventional piezoelectric sensor-based detection, and proposed detection methods, and the results were compared. The ß values of a copper single-crystal sample measured using the new and the capacitive detection methods were 2.49 and 2.1, respectively, and those obtained using the conventional piezoelectric sensor-based detection method ranged between 90 and 130. The test results confirm that the proposed field-deployable measurement method produces more consistent absolute ß values without involving the complexity of the capacitive detection method.

Nonlinear ultrasonic characterization of early degradation of fatigued Al6061-T6 with harmonic generation technique.

In this paper, a third harmonic was used to investigate microstructural changes in Al6061-T6 due to different fatigue cycles and a relationship between fatigue cycle and third order nonlinearity has been observed. Piezoelectric measurement harmonic generation technique was applied for the specimens with 0%, 55%, 75% and 85% fatigue cycles, respectively. The results shows that the third order harmonics gradually increased up to 55% and rapidly decreased after wards, it was attributed to the behavior of dislocation, dislocation-precipitation interaction and voids with increasing fatigue cycle. Further, it was verified with scanning electron microscope (SEM). We also observed that third order nonlinearity is more sensitive to small change in area of fraction of voids than second order nonlinearity after 55% fatigue life and could be a good candidate to investigate Al6061-T6 specimen with voids.

Interaction between pyridoxal kinase and pyridoxal-5-phosphate-dependent enzymes.

The interactions of two pyridoxal-5-phosphate (PLP)-dependent enzymes, alanine aminotransferase (ALT) and glutamate decarboxylase (GAD), with pyridoxal kinase (PK) were studied by fluorescence polarization as well as surface plasmon resonance techniques. The results demonstrated that PK can specifically bind to ALT and GAD. Moreover, binding profiles of both enzymes to immobilized PK were altered by excess amount of PLP. The equilibrium affinity constants for ALT in the absence and presence of PLP are 20.4 x 10(4) M(-1)and 6.7 x 10(4) M(-1), and for GAD are 37 x 10(4) M(-1)and 20.8 x 10(4) M(-1), respectively. It appears that specific interactions occur between PK and PLP-dependent enzymes, and the binding affinities of PK for PLP-dependent enzymes decrease in the presence of PLP. The results support our hypothesis that PLP transfer from PK to PLP-dependent enzymes requires a specific interaction between PK and the enzyme.