Search

Passive millimeter–wave (PMMW) scanners are widely used for personal security screening in public places due to their nonradiation and high real‐time capabilities. However, the images obtained by these scanners frequently exhibit low signal‐to‐noise ratios and contrast, presenting challenges for automated detection systems. To address this issue, we propose an efficient semantic segmentation approach, FA‐UNet, that employs a UNet architecture with a fusion attention mechanism to conduct binary classification (human body vs. background, including objects) for PMMW images. This approach incorporates a spatial attention mechanism into the lateral connections between the encoder and decoder and introduces a channel attention mechanism during the feature fusion process in the decoder. By combining these attention mechanisms, FA‐UNet leads to more precise segmentation outcomes. The segmented image is then fused with the original image using our multistage fusion method, in which, first, the two images are blended in a 1:1 ratio for object detection. Then, a new fused image is obtained by adjusting the ratio within a certain range (0.3–0.5). Finally, the object detection results are overlaid on this fused image to generate a directly displayable image. We evaluate our method using a self‐made dataset. Experimental results demonstrate that FA‐UNet can accurately segment the human body region and preserve object shapes effectively. Using the fused image for object detection helps reduce false detections caused by background noise interference while improving the detection rate of weak targets. Additionally, the fused image aids in manual image interpretation in locations with higher security inspection levels and contributes to protect the privacy of individuals undergoing inspection to the greatest extent possible. [ABSTRACT FROM AUTHOR]

Employing a sparse array is an effective method to reduce the cost of millimeter wave (MMW) imaging systems. However, the sparse array can lead to uneven MMW sampling along the array dimension, which renders the highly efficient range migration algorithm (RMA) inapplicable. While the back projection algorithm (BPA) can meet the needs of uneven sampling, its efficiency is too low. Therefore, this paper proposes a novel MMW image reconstruction algorithm, named range migration and back projection algorithm (RMBPA), which combines RMA and BPA. The RMBPA uses the RMA for focusing and solving in the mechanically scanned and range-focused directions with uniform sampling and employs the BPA for aperture synthesis in the direction with non-uniform sampling. Building upon the RMBPA, this paper introduces an innovative low-cost planar scanning MMW imaging technology based on a one-dimensional (1D) sparse array. Simulation and experimental results demonstrate that the imaging technology can achieve a spatial resolution of 5 mm in the Ka-band, clearly discerning the human silhouette and handgun model in human body imaging. The image quality is comparable to that of non-sparse array imaging under the same conditions, with imaging efficiency slightly lower than RMA but significantly higher than BPA. The technology can get a 1 m × 2 m area imaging in only 2.0 s, offering significant application value. [ABSTRACT FROM AUTHOR]

Genomic instability can be induced by nascent allopolyploidization in plants. However, most previous studies have not defined to what extent the allopolyploidy-induced rapid genomic instability represents a general response, and hence important to evolution, or merely incidental events occurring stochastically in a limited number of individuals. We report here that in a newly formed allohexaploid wheat line between tetraploid wheat Triticum turgidum subsp. durum (genome BBAA) and Aegilops tauschii (genome DD) a great majority of individual plants showed chromosomal stability and exhibited a genomic constitution similar to that of the present-day Triticum aestivum (genome BBAADD). In contrast, a single individual plant was identified at [S.sub.2], which exhibited chromosomal instability in both number and structure based on multicolor genomic in situ hybridization (mc-GISH) analysis. Accordingly, this plant also manifested extensive changes at the molecular level including loss and gain of DNA segments and DNA methylation repatterning. Remarkably, the chromosomal and molecular instabilities that presumably occurred at [S.sub.0] to [S.sub.1] and (or) in the [F.sub.1] hybrid were rapidly quenched by [S.sub.2] and followed by stable transgenerational inheritance. Our results suggest that these stochastic and individual-specific rapid genomic changes, albeit interesting, probably have not played a major role in the speciation and evolution of common wheat, T. aestivum. Key words: allopolyploidy, rapid genomic changes, genome evolution, wheat. L'allopolyploidisation naissante peut induire une instabilite genomique chez les plantes. La majorite des etudes anterieures n'ont cependant pas determine si l'instabilite genomique induite rapidement suite a l'allopolyploidisation constituait une reponse generale, et ainsi importante pour l'evolution, ou simplement des evenements se produisant de maniere stochastique chez un nombre limite d'individus. Les auteurs rapportent ici que chez une lignee de ble hexaploide recemment obtenue en croisant un ble dur tetraploide (Triticum turgidum subsp. durum; genome BBAA) avec un Aegilops tauschii (genome DD) la grande majorite des individus presentaient de l'instabilite chromosomique et une constitution genomique semblable a celle du ble contemporain (Triticum aestivum; genome BBAADD). Par contraste, une seule plante individuelle en [S.sub.2] presentait une instabilite chromosomique a la fois pour le nombre et la structure des chromosomes, telle qu'observee en hybridation genomique in situ (GISH) multicolore. Cette plante presentait egalement de nombreux changements au niveau moleculaire incluant le gain et la perte de segments d'ADN et des modifications dans la methylation de l'ADN. Remarquablement, les instabilites chromosomiques et moleculaires qui sont vraisemblablement survenues lors des generations [S.sub.0] a[S.sub.1] ou chez l'hybride [F.sub.1] ont ete rapidement compensees a la [S.sub.2] et suivies d'une transmission stable lors des generations suivantes. Ces resultats suggerent que ces changements genomiques rapides stochastiques et specifiques a chaque individu, bien qu'ils soient interessants, n'auraient vraisemblablement pas joue un role majeur dans la speciation et l'evolution chez le ble, T aestivum. Mots-cles: allopolyploidie, changements genomiques rapides, evolution genomique, ble. [Traduit par la Redaction], Introduction Allopolyploidy (interspecific hybridization prior to or followed by whole-genome doubling) is a prominent feature commonly found in many organismal taxa, and prevails in plants (Chen 2007; Chen and Ni [...]

Abstract Background Conventional prenatal screening tests, such as maternal serum tests and ultrasound scan, have limited resolution and accuracy. Methods We developed an advanced noninvasive prenatal diagnosis method based on massively parallel sequencing. The Noninvasive Fetal Trisomy (NIFTY) test, combines an optimized Student’s t-test with a locally weighted polynomial regression and binary hypotheses. We applied the NIFTY test to 903 pregnancies and compared the diagnostic results with those of full karyotyping. Results 16 of 16 trisomy 21, 12 of 12 trisomy 18, two of two trisomy 13, three of four 45, X, one of one XYY and two of two XXY abnormalities were correctly identified. But one false positive case of trisomy 18 and one false negative case of 45, X were observed. The test performed with 100% sensitivity and 99.9% specificity for autosomal aneuploidies and 85.7% sensitivity and 99.9% specificity for sex chromosomal aneuploidies. Compared with three previously reported z-score approaches with/without GC-bias removal and with internal control, the NIFTY test was more accurate and robust for the detection of both autosomal and sex chromosomal aneuploidies in fetuses. Conclusion Our study demonstrates a powerful and reliable methodology for noninvasive prenatal diagnosis.

Abstract Background Alteration in gene expression resulting from allopolyploidization is a prominent feature in plants, but its spectrum and extent are not fully known. Common wheat (Triticum aestivum) was formed via allohexaploidization about 10,000 years ago, and became the most important crop plant. To gain further insights into the genome-wide transcriptional dynamics associated with the onset of common wheat formation, we conducted microarray-based genome-wide gene expression analysis on two newly synthesized allohexaploid wheat lines with chromosomal stability and a genome constitution analogous to that of the present-day common wheat. Results Multi-color GISH (genomic in situ hybridization) was used to identify individual plants from two nascent allohexaploid wheat lines between Triticum turgidum (2n = 4x = 28; genome BBAA) and Aegilops tauschii (2n = 2x = 14; genome DD), which had a stable chromosomal constitution analogous to that of common wheat (2n = 6x = 42; genome BBAADD). Genome-wide analysis of gene expression was performed for these allohexaploid lines along with their parental plants from T. turgidum and Ae. tauschii, using the Affymetrix Gene Chip Wheat Genome-Array. Comparison with the parental plants coupled with inclusion of empirical mid-parent values (MPVs) revealed that whereas the great majority of genes showed the expected parental additivity, two major patterns of alteration in gene expression in the allohexaploid lines were identified: parental dominance expression and non-additive expression. Genes involved in each of the two altered expression patterns could be classified into three distinct groups, stochastic, heritable and persistent, based on their transgenerational heritability and inter-line conservation. Strikingly, whereas both altered patterns of gene expression showed a propensity of inheritance, identity of the involved genes was highly stochastic, consistent with the involvement of diverse Gene Ontology (GO) terms. Nonetheless, those genes showing non-additive expression exhibited a significant enrichment for vesicle-function. Conclusions Our results show that two patterns of global alteration in gene expression are conditioned by allohexaploidization in wheat, that is, parental dominance expression and non-additive expression. Both altered patterns of gene expression but not the identity of the genes involved are likely to play functional roles in stabilization and establishment of the newly formed allohexaploid plants, and hence, relevant to speciation and evolution of T. aestivum.