Diversified Fluid Antenna Designs for Mobile Communications

In current mobile communications, massive MIMO is an essential technology, especially for mm-wave 5G and future 6G mobile systems. However, implementing MIMO antennas for such applications is challenging due to the physical limitations of mobile devices. To address this issue, this study proposes novel surface wave-based fluid antennas. The proposed antennas achieve radiation pattern reconfigurability with a compact design of 10 mm x 33 mm 5 mm at a frequency range of 24 to 30 GHz, which is small enough for portable equipment. These antennas use only one feeding port, simplifying the feeding mechanism compared to MIMO systems that may require multiple RF chains. The fluid channel can also be easily scaled for different shapes and sizes with the proposed surface wave launcher. The proposed fluid antennas were simulated, fabricated, assembled, and measured within UCL facilities. Results show that these antennas achieve radiation pattern diversity, with an average RPDR (radiation pattern dynamic range) of up to 10 dB in the targeted mm-wave 5G frequency bands from 24 to 30 GHz. Radiation pattern dynamic range is a new indicator used to evaluate the proposed fluid antennas' radiation pattern reconfigurability. The proposed antennas offer several notable contributions. Firstly, they demonstrate the successful development of fluid antennas with radiation pattern reconfigurability. Secondly, the antennas feature a relatively simple structure, utilizing a 3D-printed container and PCB board, which enables cost-effective manufacturing and makes the antennas accessible to a wider range of users. Thirdly, the proposed fluid antenna incorporates a fluid control system and a comprehensive measurement setup specifically tailored for fluid antennas. These additions enhance the overall viability and practicality of the antenna design. Lastly, the introduction of the RPDR indicator provides a valuable tool for analyzing the radiation pattern reconfigurability of similar antennas. This indicator facilitates performance comparisons and aids in the refinement of future antenna designs

ELODI: Ensemble Logit Difference Inhibition for Positive-Congruent Training

Negative flips are errors introduced in a classification system when a legacy model is replaced with a new one. Existing methods to reduce the negative flip rate (NFR) either do so at the expense of overall accuracy using model distillation, or use ensembles, which multiply inference cost prohibitively. We present a method to train a classification system that achieves paragon performance in both error rate and NFR, at the inference cost of a single model. Our method introduces a generalized distillation objective, Logit Difference Inhibition (LDI), that penalizes changes in the logits between the new and old model, without forcing them to coincide as in ordinary distillation. LDI affords the model flexibility to reduce error rate along with NFR. The method uses a homogeneous ensemble as the reference model for LDI, hence the name Ensemble LDI, or ELODI. The reference model can then be substituted with a single model at inference time. The method leverages the observation that negative flips are typically not close to the decision boundary, but often exhibit large deviations in the distance among their logits, which are reduced by ELODI.Comment: Tech repor

Preparation and Characterization of a Lovastatin-Loaded Protein-Free Nanostructured Lipid Carrier Resembling High-Density Lipoprotein and Evaluation of its Targeting to Foam Cells

This study was designed to investigate whether a non-protein nanostructured lipid carrier (NLC) resembling high-density lipoprotein (HDL) could deliver a hydrophobic anti-atherogenic drug, lovastatin, to foam cells. Lovastatin-loaded NLC (LT-NLC) was prepared by a nanoprecipitation/solvent diffusion method. The LT-NLC-apoprotein (LT-NLC-apo) was prepared by incubating LT-NLC with native HDL. The physicochemical parameters of LT-NLC were characterized in terms of particle size, zeta potential, morphology, entrapment efficiency, and crystallization behavior. Targeting behavior and mechanism were demonstrated by the incubation of LT-NLC-apo with a RAW 264.7 macrophage-derived foam cell model in the presence or absence of very-low-density lipoprotein (VLDL) and lipase. The results showed that LT-NLC was solid spherical or oval in shape with an average diameter of 13.8 ± 2.2 nm, zeta potential of −29.3 ± 0.2 mV and entrapment efficiency of 96.2 ± 1.3%. Phagocytosis studies showed that uptake of LT-NLC-apo by macrophages was significantly lower than LT-NLC (p < 0.01), suggesting that LT-NLC-apo could possibly escape recognition from macrophages in vivo. The uptake was increased twofold when LT-NLC-apo was incubated with transfected foam cells containing VLDL and lipase. These results indicated that non-protein NLC resembling HDL could be a useful tool to deliver lipophilic anti-atherogenic drugs to foam cells, and that uptake could be enhanced by the VLDL receptor pathway