A novel low-profile wideband reconfigurable CP antenna array

© Institution of Engineering and Technology.All Rights Reserved. For future wireless communications, cost-effective, low-profile circular polarization (CP) antennas with wide bandwidth and high directivity are highly desirable to increase system capacity and suppress polarization mismatch. In this paper, a wideband circular polarization antenna array integrated with a polarization-independent artificial magnetic conductor (AMC) is reported that meets the demands. First, a wideband CP reconfigurable antenna with a pair of cross-bowtie radiators and a metal ground is presented to achieve a fractional bandwidth of 35.9%. By replacing the metal ground with a polarization-independent AMC ground, the antenna profile is reduced from 0.25λ0 to 0.05λ0 with only a slight bandwidth decrease. A wideband CP reconfigurable 4-element linear array is achieved using four of those elements. It is low profile (0.05 λ0), and has a wide operating bandwidth (21.7%), and a high realized gain (13 dBic)

Conformal Transmitarrays for Unmanned Aerial Vehicles Aided 6G Networks

Unmanned aerial vehicles (UAVs) aided wireless communications promise to provide high-speed cost-effective wireless connectivity without needing fixed infrastructure coverage. They are a key technology enabler for sixth generation (6G) wireless networks, where a three-dimensional coverage including space, aero and terrestrial networks are to be deployed to guarantee seamless service continuity and reliability. Owing to the aerodynamic requirements, it is highly desirable to employ conformal antennas that can follow the shapes of the UAVs to reduce the extra drag and fuel consumption. To enable hundred giga-bits-per-second (Gb/s) data rates and massive connectivity for 6G networks, conformal antenna arrays featured with high gains and beam scanning/multiple beams are demanded for millimeter-wave and higher-frequency-range communications. However, new challenges exist in designing and implementing high-gain conformal arrays for UAV platforms. In this article, we overview the recent advances in conformal transmitarrays for UAV-based wireless communications, introducing new design methodologies and high-lighting new opportunities to be exploited

An Elliptical Cylindrical Shaped Transmitarray for Wide-Angle Multibeam Applications

A transmitarray antenna with an elliptical cylindrical shape is presented for a wide-angle multibeam radiation in this paper. The transmitarray has a cylindrical radiating aperture with an elliptical cross section, namely, elliptical cylindrical shape. Multiple feeds can be placed on the middle horizontal plane to realize multiple beams. Inspired by a two-dimensional (2-D) Ruze lens, the antenna shape and the phase compensation are jointly designed according to the desired maximal beam direction. Innovative methods including a feed refocusing analysis and a virtual focal length are utilized to achieve the phase compensation across the three-dimensional (3-D) aperture for multiple beam radiations with a small scanning loss. In order to validate the proposed antenna, a prototype operating in the millimeter-wave E band has been designed, fabricated and measured. By changing the position of the feeding gain horn along the refocusing arc, the main beam of antenna can be scanned to eleven directions. The measured peak boresight realized gain is 27 dBi at 70.5 GHz and a beam coverage of ±43° with a less than 2.7-dB scanning loss is obtained

Chromatin remodelling complex dosage modulates transcription factor function in heart development

Dominant mutations in cardiac transcription factor genes cause human inherited congenital heart defects (CHDs); however, their molecular basis is not understood. Interactions between transcription factors and the Brg1/Brm-associated factor (BAF) chromatin remodelling complex suggest potential mechanisms; however, the role of BAF complexes in cardiogenesis is not known. In this study, we show that dosage of Brg1 is critical for mouse and zebrafish cardiogenesis. Disrupting the balance between Brg1 and disease-causing cardiac transcription factors, including Tbx5, Tbx20 and Nkx2–5, causes severe cardiac anomalies, revealing an essential allelic balance between Brg1 and these cardiac transcription factor genes. This suggests that the relative levels of transcription factors and BAF complexes are important for heart development, which is supported by reduced occupancy of Brg1 at cardiac gene promoters in Tbx5 haploinsufficient hearts. Our results reveal complex dosage-sensitive interdependence between transcription factors and BAF complexes, providing a potential mechanism underlying transcription factor haploinsufficiency, with implications for multigenic inheritance of CHDs

Complex SUMO-1 Regulation of Cardiac Transcription Factor Nkx2-5

Reversible post-translational protein modifications such as SUMOylation add complexity to cardiac transcriptional regulation. The homeodomain transcription factor Nkx2-5/Csx is essential for heart specification and morphogenesis. It has been previously suggested that SUMOylation of lysine 51 (K51) of Nkx2-5 is essential for its DNA binding and transcriptional activation. Here, we confirm that SUMOylation strongly enhances Nkx2-5 transcriptional activity and that residue K51 of Nkx2-5 is a SUMOylation target. However, in a range of cultured cell lines we find that a point mutation of K51 to arginine (K51R) does not affect Nkx2-5 activity or DNA binding, suggesting the existence of additional Nkx2-5 SUMOylated residues. Using biochemical assays, we demonstrate that Nkx2-5 is SUMOylated on at least one additional site, and this is the predominant site in cardiac cells. The second site is either non-canonical or a “shifting” site, as mutation of predicted consensus sites and indeed every individual lysine in the context of the K51R mutation failed to impair Nkx2-5 transcriptional synergism with SUMO, or its nuclear localization and DNA binding. We also observe SUMOylation of Nkx2-5 cofactors, which may be critical to Nkx2-5 regulation. Our data reveal highly complex regulatory mechanisms driven by SUMOylation to modulate Nkx2-5 activity

Diagnostic value of fine-needle aspiration biopsy for breast mass: a systematic review and meta-analysis

<p>Abstract</p> <p>Background</p> <p>Fine-needle aspiration biopsy (FNAB) of the breast is a minimally invasive yet maximally diagnostic method. However, the clinical use of FNAB has been questioned. The purpose of our study was to establish the overall value of FNAC in the diagnosis of breast lesions.</p> <p>Methods</p> <p>After a review and quality assessment of 46 studies, sensitivity, specificity and other measures of accuracy of FNAB for evaluating breast lesions were pooled using random-effects models. Summary receiver operating characteristic curves were used to summarize overall accuracy. The sensitivity and specificity for the studies data (included unsatisfactory samples) and underestimation rate of unsatisfactory samples were also calculated.</p> <p>Results</p> <p>The summary estimates for FNAB in diagnosis of breast carcinoma were as follows (unsatisfactory samples was temporarily exluded): sensitivity, 0.927 (95% confidence interval [CI], 0.921 to 0.933); specificity, 0.948 (95% CI, 0.943 to 0.952); positive likelihood ratio, 25.72 (95% CI, 17.35 to 28.13); negative likelihood ratio, 0.08 (95% CI, 0.06 to 0.11); diagnostic odds ratio, 429.73 (95% CI, 241.75 to 763.87); The pooled sensitivity and specificity for 11 studies, which reported unsatisfactory samples (unsatisfactory samples was considered to be positive in this classification) were 0.920 (95% CI, 0.906 to 0.933) and 0.768 (95% CI, 0.751 to 0.784) respectively. The pooled proportion of unsatisfactory samples that were subsequently upgraded to various grade cancers was 27.5% (95% CI, 0.221 to 0.296).</p> <p>Conclusions</p> <p>FNAB is an accurate biopsy for evaluating breast malignancy if rigorous criteria are used. With regard to unsatisfactory samples, futher invasive procedures are required in order to minimize the chance of a missed diagnosis of breast cancer.</p

Design and analysis of a wide angle impedance matching metasurface for wideband antenna arrays

© Institution of Engineering and Technology.All Rights Reserved. A wide bandwidth, low profile, double sided, wide angle impedance matching metasurface is reported. It alleviates the well-known problem of impedance mismatch caused by mutual coupling when an array is in its scan mode. Each unit cell of the metasurface contains two multi-resonant, tightly-coupled unequal arm Jerusalem cross elements on the top and bottom sides of a thin substrate. Each element consists of two orthogonal capacitively loaded strips. The wide bandwidth of the metasurface is achieved by tightly coupling these multi-resonant elements. The metasurface is capable of facilitating wide angle scanning over a 6:1 impedance bandwidth without the need for bulky dielectrics or multi-layered structures