Research on a Sound Source Localization Method for UAV Detection Based on Improved Empirical Mode Decomposition.

To address the challenge of accurately locating unmanned aerial vehicles (UAVs) in situations where radar tracking is not feasible and visual observation is difficult, this paper proposes an innovative acoustic source localization method based on improved Empirical Mode Decomposition (EMD) within an adaptive frequency window. In this study, the collected flight signals of UAVs undergo smoothing filtering. Additionally, Robust Empirical Mode Decomposition (REMD) is applied to decompose the signals into Intrinsic Mode Function (IMF) components for spectrum analysis. We introduce a sliding frequency window with adjustable bandwidth, which is automatically determined using a Grey Wolf Optimizer (GWO) with a sliding index. This window is used to lock and extract specific frequencies from the IMFs. Based on predefined criteria, the extracted IMF components are reconstructed, and trigger signal times are analyzed and recorded from these reconstructed IMFs. The time differences between sensor receptions are then calculated. Furthermore, this study introduces the Chan-Taylor localization algorithm based on weighted least squares. This advanced algorithm takes sensor time delay parameters as input and solves a set of nonlinear equations to determine the target's location. Simulations and real-world signal tests are used to validate the robustness and performance of the proposed method. The results indicate that the localization error remains below 5% within a 15 m × 15 m measurement area. This provides an efficient and real-time method for detecting the location of small UAVs.

Characterization of fragment sizes, copy number aberrations and 4-mer end motifs in cell-free DNA of hepatocellular carcinoma for enhanced liquid biopsy-based cancer detection.

Circulating cell-free DNA (cfDNA) fragmentomics, which encompasses the measurement of cfDNA length and short nucleotide motifs at the ends of cfDNA molecules, is an emerging field for cancer diagnosis. The utilization of cfDNA fragmentomics for the diagnosis of patients with hepatocellular carcinoma (HCC) caused by hepatitis B virus (HBV) is currently limited. In this study, we utilized whole-genome sequencing data of cfDNA in samples from patients with HCC (n = 197) and HBV (n = 187) to analyze the association of fragment size selection (< 150 bp) with tumor fraction (TF), copy number variation (CNV) alterations and the change in the proportion of 4-mer end motifs in HCC and HBV samples. Our analyses identified five typical CNV markers (i.e. loss in chr1p, chr4q and chr8p, and gain in chr1q and chr8q) in cfDNA with a cumulatively positive rate of ˜ 95% in HCC samples. Size selection (< 150 bp) significantly enhanced TF and CNV signals in HCC samples. Additionally, three 4-mer end motifs (CCCA, CCTG and CCAG) were identified as preferred end motifs in HCC samples. We identified 139 end motifs significantly associated with fragment size that showed similar patterns of associations between patients with HCC and HBV, suggesting that end motifs might be inherently coupled with fragment size by a ubiquitous mechanism. Here we conclude that CNV markers, fragment size selection and end-motif pattern in cfDNA have potential for effective detection of patients with HCC.

A model for the impact of FFPE section thickness on gene copy number measurement by FISH.

Fluorescent in situ hybridization (FISH) assays to detect gene amplification such as HER2 or MET in tumors are used for prognosis evaluation and selection of targeted therapies. Although FISH guidelines recommended 4~6 µm FFPE sections, many laboratories use 2~3 µm sections, which is a common practice for H&E staining and immunohistochemistry. A former study concluded that section thickness did not affect FISH results. We found, however, that thinner FFPE sections may lead to false negative results for gene amplification. A mathematic model was constructed and cell-line based controls with known gene copy number were prepared, and the model had a reasonable fit with the experimental data. The model revealed that even when counting the apparently full-sized nuclear images, many of them have partial volumes, which leads to under-estimation of gene copy number. Therefore, improperly thinner sections are prone to give false negative results, and thicker sections give a better approximation to the true value. The discrepancy between this and the former study was discussed. In summary, the model applies generally to FISH/ISH detection of gene copy number, and section thickness is an important parameter to control for precision medicine research, assay development, clinical trials and daily practice in pathology laboratory.

PEG-protein interaction induced contraction of NalD chains.

In a recent attempt to crystallize a regulator of MexAB-OprM multi-drug efflux systems in Pseudomonas aeruginosa (NalD), we found that adding polyethylene glycol (PEG3350, Mw = 3,350 g/mol) into the protein solution increases the speed of NalD migration in gel electrophoresis, signaling a smaller hydrodynamic size. At first we conjectured that NalD was degraded unexpectedly by PEG; however, we found that there was no change in its molar mass by MALDI-TOF characterization. Moreover, we found that adding polyacrylic acid (PAA) into the solution mixture returned the NalD migration to its normal speed. Furthermore, our analytic ultracentrifugation and dynamic laser light scattering results directly reveal that NalD interacts with PEG so that individual NalD chains gradually shrink as more PEG chains are added in the range of 10-50 mg/mL. Size exclusion chromatography also confirms that the NalD chain shrinks in the presence of PEG. A combination of these results indicates that PEG3350 chains can complex with NalD to induce an intra-protein chain contraction, presumably via the formation of hydrogen bond between -C-O-C- on PEG and -COOH on NalD, resulting in a smaller hydrodynamic size (faster migration) and a higher apparent molar mass. Note that because the presence of PEG affects osmotic pressure, it is considered to be a precipitator of protein crystallization. Our current finding reveals that the interaction of PEG/protein may play a significant role in protein crystallization. The complexation potentially makes the protein chain segments less flexible, and consequently makes crystallization easier. Hopefully, our current results will stimulate further studies in this direction.