An Ultra-wideband Off-axis Reflector Lens

The paper describes the design, fabrication and characterization of an ultra-wideband off-axis reflector lens operating between 6.8 GHz and 16.8 GHz. The lens is constructed using a single layer metasurface, consisting of a single ring with two equal openings. The design achieves an efficiency greater than 80% polarization conversion and a cross-polarization gain of 10 dB at the center frequency. The experimental results are in good agreement with the numerical simulations

Characterization of a compact wideband microwave metasurface lens for cryogenic applications

In this paper, we present characterization of a compact flat microwave lens operating between 6 GHz and 14 GHz using a near field scanning system. An X-band horn antenna and open-end rectangular waveguide were used as an illumination source and probe, respectively. |S21| is measured as the probe antenna moves on a plane orthogonal to the optical axis vertically and horizontally. The lens is made of a metasurface layer that is sandwiched by two layers of cross-oriented gratings. The overall dimension of the lens is 10 cm in diameter and 0.57 cm in thickness. The measurement results show that the lens's focal length is 8 cm, and the beamwidth (full width at half maximum (FWHM)) is 3.5 cm, A transmission efficiency of over 90% and a cross-polarization gain of 25 dB were achieved over the entire bandwidth. The measurement results at room temperature are in good agreement with numerical simulations. The proposed lens will be used in a cryogenic environment e.g. dilution refrigerators for quantum computing systems. More results at cryogenic temperature e.g, below 30 K will be shown at the conference

A Splice Isoform of DNedd4, DNedd4-Long, Negatively Regulates Neuromuscular Synaptogenesis and Viability in Drosophila

Neuromuscular (NM) synaptogenesis is a tightly regulated process. We previously showed that in flies, Drosophila Nedd4 (dNedd4/dNedd4S) is required for proper NM synaptogenesis by promoting endocytosis of commissureless from the muscle surface, a pre-requisite step for muscle innervation. DNedd4 is an E3 ubiquitin ligase comprised of a C2-WW(x3)-Hect domain architecture, which includes several splice isoforms, the most prominent ones are dNedd4-short (dNedd4S) and dNedd4-long (dNedd4Lo).We show here that while dNedd4S is essential for NM synaptogenesis, the dNedd4Lo isoform inhibits this process and causes lethality. Our results reveal that unlike dNedd4S, dNedd4Lo cannot rescue the lethality of dNedd4 null (DNedd4(T121FS)) flies. Moreover, overexpression of UAS-dNedd4Lo specifically in wildtype muscles leads to NM synaptogenesis defects, impaired locomotion and larval lethality. These negative effects of dNedd4Lo are ameliorated by deletion of two regions (N-terminus and Middle region) unique to this isoform, and by inactivating the catalytic activity of dNedd4Lo, suggesting that these unique regions, as well as catalytic activity, are responsible for the inhibitory effects of dNedd4Lo on synaptogenesis. In accord with these findings, we demonstrate by sqRT-PCR an increase in dNedd4S expression relative to the expression of dNedd4Lo during embryonic stages when synaptogenesis takes place.Our studies demonstrate that splice isoforms of the same dNedd4 gene can lead to opposite effects on NM synaptogenesis

Role of DNedd4 Splice Isoforms in Neuromuscular Synaptogenesis in Drosophila Melanogaster

Drosophila Nedd4 (DNedd4), an E3 ubiquitin ligase, is known to be involved in neuromuscular (NM) synaptogenesis during embryogenesis. To further elucidate its mechanism and function in this process, two major splice isoforms, dNedd4 short (dNedd4S) and dNedd4 long (dNedd4L), were studied. My work shows that while dNedd4S positively regulates NM synaptogenesis, dNedd4L plays a negative role in this process. Unique regions in dNedd4L, including the N-terminal 66 amino acid-long sequence (but not the putative dAkt phosphorylation site) and the middle 159 amino acid-long sequence, as well as the catalytic site, are required for its negative function. I proposed one possible mechanism of dNedd4L acting as a negative regulator of dNedd4S. Results from my studies of the putative effect of dNedd4L on the catalytic activity of dNedd4S in vitro, as well as on the function of dNedd4S towards Comm in Drosophila S2 cells, did not support this mechanism.MAS