Multifunctional and compact 3D FMCW MIMO radar system with rectangular array for medium-range applications

Miralles-Navarro, E.; Multerer, T.; Ganis, A.; Schoenlinner, B.; Prechtel, U.; Meusling, A.; Mietzner, J.... (2018). Multifunctional and compact 3D FMCW MIMO radar system with rectangular array for medium-range applications. IEEE Aerospace and Electronic Systems Magazine. 33(4):46-54. https://doi.org/10.1109/MAES.2018.160277S465433

A portable 3D Imaging FMCW MIMO Radar Demonstrator with a 24x24 Antenna Array for Medium Range Applications

© 2018 IEEE. Personal use of this material is permitted. Permissíon from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertisíng or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.[EN] Multiple-input multiple-output (MIMO) radars have been shown to improve target detection for surveillance applications thanks to their proven high-performance properties. In this paper, the design, implementation, and results of a complete 3-D imaging frequency-modulated continuous-wave MIMO radar demonstrator are presented. The radar sensor working frequency range spans between 16 and 17 GHz, and the proposed solution is based on a 24-transmitter and 24-receiver MIMO radar architecture, implemented by timedivision multiplexing of the transmit signals. A modular approach based on conventional low-cost printed circuit boards is used for the transmit and receive systems. Using digital beamforming algorithms and radar processing techniques on the received signals, a high-resolution 3-D sensing of the range, azimuth, and elevation can be calculated. With the current antenna configuration, an angular resolution of 2.9° can be reached. Furthermore, by taking advantage of the 1-GHz bandwidth of the system, a range resolution of 0.5 m is achieved. The radio-frequency front-end, digital system and radar signal processing units are here presented. The medium-range surveillance potential and the high-resolution capabilities of the MIMO radar are proved with results in the form of radar images captured from the field measurements.Ganis, A.; Miralles-Navarro, E.; Schoenlinner, B.; Prechtel, U.; Meusling, A.; Heller, C.; Spreng, T.... (2018). A portable 3D Imaging FMCW MIMO Radar Demonstrator with a 24x24 Antenna Array for Medium Range Applications. IEEE Transactions on Geoscience and Remote Sensing. 56(1):298-312. https://doi.org/10.1109/TGRS.2017.2746739S29831256

Functional Characterization of the HuR:CD83 mRNA Interaction

Maturation of dendritic cells (DC) is characterized by expression of CD83, a surface protein that appears to be necessary for the effective activation of naïve T-cells and T-helper cells by DC. Lately it was shown that CD83 expression is regulated on the posttranscriptional level by interaction of the shuttle protein HuR with a novel posttranscriptional regulatory RNA element (PRE), which is located in the coding region of the CD83 transcript. Interestingly, this interaction commits the CD83 mRNA to efficient nuclear export via the CRM1 pathway. To date, however, the structural basis of this interaction, which potentially involves three distinct RNA recognition motifs (RRM1–3) in HuR and a complex three-pronged RNA stem-loop element in CD83 mRNA, has not been investigated in detail. In the present work we analyzed this interaction in vitro and in vivo using various HuR- and CD83 mRNA mutants. We are able to demonstrate that both, RRM1 and RRM2 are crucial for binding, whereas RRM3 as well as the HuR hinge region contributed only marginally to this protein∶RNA interaction. Furthermore, mutation of uridine rich patches within the PRE did not disturb HuR:CD83 mRNA complex formation while, in contrast, the deletion of specific PRE subfragments from the CD83 mRNA prevented HuR binding in vitro and in vivo. Interestingly, the observed inhibition of HuR binding to CD83 mRNA does not lead to a nuclear trapping of the transcript but rather redirected this transcript from the CRM1- towards the NXF1/TAP-specific nuclear export pathway. Thus, the presence of a functional PRE permits nucleocytoplasmic trafficking of the CD83 transcript via the CRM1 pathway

Microcavity-integrated graphene photodetector

The monolithic integration of novel nanomaterials with mature and established technologies has considerably widened the scope and potential of nanophotonics. For example, the integration of single semiconductor quantum dots into photonic crystals has enabled highly efficient single-photon sources. Recently, there has also been an increasing interest in using graphene - a single atomic layer of carbon - for optoelectronic devices. However, being an inherently weak optical absorber (only 2.3 % absorption), graphene has to be incorporated into a high-performance optical resonator or waveguide to increase the absorption and take full advantage of its unique optical properties. Here, we demonstrate that by monolithically integrating graphene with a Fabry-Perot microcavity, the optical absorption is 26-fold enhanced, reaching values >60 %. We present a graphene-based microcavity photodetector with record responsivity of 21 mA/W. Our approach can be applied to a variety of other graphene devices, such as electro-absorption modulators, variable optical attenuators, or light emitters, and provides a new route to graphene photonics with the potential for applications in communications, security, sensing and spectroscopy.Comment: 19 pages, 4 figure

On-chip picosecond pulse detection and generation using graphene photoconductive switches

We report on the use of graphene for room temperature on-chip detection and generation of pulsed terahertz (THz) frequency radiation, exploiting the fast carrier dynamics of light-generated hot carriers, and compare our results with conventional low-temperature-grown gallium arsenide (LT-GaAs) photoconductive (PC) switches. Coupling of picosecond-duration pulses from a biased graphene PC switch into Goubau line waveguides is also demonstrated. A Drude transport model based on the transient photoconductance of graphene is used to describe the mechanism for both detection and generation of THz radiation

Ultrafast electronic read-out of diamond NV centers coupled to graphene

Nonradiative transfer processes are often regarded as loss channels for an optical emitter1, since they are inherently difficult to be experimentally accessed. Recently, it has been shown that emitters, such as fluorophores and nitrogen vacancy centers in diamond, can exhibit a strong nonradiative energy transfer to graphene. So far, the energy of the transferred electronic excitations has been considered to be lost within the electron bath of the graphene. Here, we demonstrate that the trans-ferred excitations can be read-out by detecting corresponding currents with picosecond time resolution. We electrically detect the spin of nitrogen vacancy centers in diamond electronically and con-trol the nonradiative transfer to graphene by electron spin resonance. Our results open the avenue for incorporating nitrogen vacancy centers as spin qubits into ultrafast electronic circuits and for harvesting non-radiative transfer processes electronically

CRM1-mediated nuclear export of CD83 mRNA PRE.

<p><b>A.</b> COS7 cells were transiently transfected either with an expression vector encoding for human CD83 cDNA flanked by the homologous 5′- and 3′-UTR (wt; lane 1–6) or with a related vector in which essential PRE sequences were deleted (PREΔSubL1–3; lane 7–12). At day two posttransfection cultures were exposed to 10 nM of the CRM1 inhibitor LMB or DMSO (solvent control) for 8 hours. Total, cytoplasmic and nuclear RNA was isolated, subjected to CD83- and GAPDH-specific (negative control) PCR and analyzed by gel electrophoresis. <b>B.</b> Quantitative real-time PCR of the RNA probes shown in panel A. RNA ratios +LMB/−LMB are depicted. <b>C.</b> Total, cytoplasmic and nuclear RNA was isolated from cell cultures which were cotransfected with the CD83 PREΔSubL1–3 expression vector and either a construct expressing four tandem repeats of the MPMV CTE (4×CTE) or the respective parental vector (negative control). For NXF1/TAP-independent control, mitochondrial cytochrome C oxidase mRNA was detected in total and cytoplasmic RNA, while GAPDH-specific transcripts were detected in nuclear RNA. <b>D.</b> Quantitative real-time PCR of the RNA probes shown in panel C. RNA ratios +/− NXF1/TAP inactivation (+CTE/−CTE) are depicted.</p

HuR binds in a specific manner to the CD83 PRE RNA region.

<p><b>A.</b> Increasing amounts of bacterial expressed GST-HuR protein was incubated either with the radiolabelled CD83 mRNA wildtype (wt) coding sequence (CD83wt; lane 1–7) or the respective probe lacking the HuR target sequence PRE (CD83ΔPRE; lane 8–14). Complex formation was visualized by gel retardation assay and autoradiography. Lane 1: CD83wt RNA alone; lane 2: GST negative control; lane 3–7 increasing amounts of GST-HuR (0.095–0.475 µM); lane 8: CD83ΔPRE alone; lane 9: GST negative control; lane 10–14: increasing amounts of GST-HuR (0.095–0.475 µM). <b>B.</b> Analysis of PRE binding specificity by competition experiments. GST-HuR protein (lane 2–4 and lane 11–13: 0.119 µM, 0.238 µM, 0.475 µM, respectively; lane 5–9 and 14–18: 0.475 µM, respectively) or GST (1 µM) for negative control (lane 1 and 10) was incubated together with radiolabelled CD83wt PRE mRNA and analyzed as before. Increasing amounts (1–5 fold excess over CD83wt PRE mRNA) of either unlabelled HIV-1 RRE RNA (lane 5–9) or unlabelled TNFα ARE RNA (lane 14–18) were added to individual binding reactions.</p