16 research outputs found
Random Noise Signal Processing
Pulse echo flaw detection systems have found extensive use in industry for quality control of many types of metal and ceramic components. The random signal flaw detection system described in this paper provides an increase in sensitivity of several orders of magnitude compared to conventional pulse echo systems.
Following a review of the theory of system operation, we present some recently obtained results of our system on materials which are strongly sound absorbing, including ceramics, plastics and metals as well as material s which have large grains. In addition to detecting flaws in strongly absorbing materials we feel that this system might also be utilized as a way of estimating grain size, inclusion size or porosity
Comparison of spread spectrum and pulse signal excitation for split spectrum techniques composite imaging
[EN] Ultrasonic imaging of composites was investigated. Glass and carbon fiber
reinforced plastic produced by resin transfer molding and prepreg forming were analyzed. In
some of the samples air bubbles were trapped during RTM (resin transfer molding) process and
interlayer gaps were present in prepreg technology samples. One of the most expected
techniques to apply in such case is the Split Spectrum processing. On the other hand such
signals require specific processing to reliably reconstruct the temporal position of the defect
reflection. Correlation processing can be used for signal compression or Wiener filtering can be
applied for spectral content equalisation. Pulse signals are simple to generate, but lack the
possibility to alter the signal’s spectrum shape. Spread spectrum signals offer a powerful tool
for signal energy over frequency band increase and resolution enhancement. CW (continuous
wave) burst has high energy but lacks the bandwidth needed for SSP (spread spectrum
processing). The aim of the investigation was to compare the performance of the above signals
in case of composite imaging, when various Split Spectrum Processing techniques are used
with preceding Wiener processing for spectral content compensation. Resulting composite
signals and images obtained are presented. Structural noise removal performance was
evaluated as Receiver Operating Characteristics (ROC).This research (acquisition system and spread spectrum signals) was funded by a grant (No. MIP058/2012) from the Research Council of Lithuania. SSP part was supported by PROMETEO 2010/40.Svilainis, L.; Kitov, S.; Rodriguez Martinez, A.; Vergara DomĂnguez, L.; Dumbrava, V.; Chaziachmetovas, A. (2012). Comparison of spread spectrum and pulse signal excitation for split spectrum techniques composite imaging. IOP Conference Series: Materials Science and Engineering. 42:5-9. https://doi.org/10.1088/1757-899X/42/1/012007S594
Tar DNA Binding Protein-43 (TDP-43) Associates with Stress Granules: Analysis of Cultured Cells and Pathological Brain Tissue
Tar DNA Binding Protein-43 (TDP-43) is a principle component of inclusions in many cases of frontotemporal lobar degeneration (FTLD-U) and amyotrophic lateral sclerosis (ALS). TDP-43 resides predominantly in the nucleus, but in affected areas of ALS and FTLD-U central nervous system, TDP-43 is aberrantly processed and forms cytoplasmic inclusions. The mechanisms governing TDP-43 inclusion formation are poorly understood. Increasing evidence indicates that TDP-43 regulates mRNA metabolism by interacting with mRNA binding proteins that are known to associate with RNA granules. Here we show that TDP-43 can be induced to form inclusions in cell culture and that most TDP-43 inclusions co-localize with SGs. SGs are cytoplasmic RNA granules that consist of mixed protein - RNA complexes. Under stressful conditions SGs are generated by the reversible aggregation of prion-like proteins, such as TIA-1, to regulate mRNA metabolism and protein translation. We also show that disease-linked mutations in TDP-43 increased TDP-43 inclusion formation in response to stressful stimuli. Biochemical studies demonstrated that the increased TDP-43 inclusion formation is associated with accumulation of TDP-43 detergent insoluble complexes. TDP-43 associates with SG by interacting with SG proteins, such as TIA-1, via direct protein-protein interactions, as well as RNA-dependent interactions. The signaling pathway that regulates SGs formation also modulates TDP-43 inclusion formation. We observed that inclusion formation mediated by WT or mutant TDP-43 can be suppressed by treatment with translational inhibitors that suppress or reverse SG formation. Finally, using Sudan black to quench endogenous autofluorescence, we also demonstrate that TDP-43 positive-inclusions in pathological CNS tissue co-localize with multiple protein markers of stress granules, including TIA-1 and eIF3. These data provide support for accumulating evidence that TDP-43 participates in the SG pathway