Specific Beamforming for Multi-UAV Networks: A Dual Identity-based ISAC Approach

Beam alignment is essential to compensate for the high path loss in the millimeter-wave (mmWave) Unmanned Aerial Vehicle (UAV) network. The integrated sensing and communication (ISAC) technology has been envisioned as a promising solution to enable efficient beam alignment in the dynamic UAV network. However, since the digital identity (D-ID) is not contained in the reflected echoes, the conventional ISAC solution has to either periodically feed back the D-ID to distinguish beams for multi-UAVs or suffer the beam errors induced by the separation of D-ID and physical identity (P-ID). This paper presents a novel dual identity association (DIA)-based ISAC approach, the first solution that enables specific, fast, and accurate beamforming towards multiple UAVs. In particular, the P-IDs extracted from echo signals are distinguished dynamically by calculating the feature similarity according to their prevalence, and thus the DIA is accurately achieved. We also present the extended Kalman filtering scheme to track and predict P-IDs, and the specific beam is thereby effectively aligned toward the intended UAVs in dynamic networks. Numerical results show that the proposed DIA-based ISAC solution significantly outperforms the conventional methods in association accuracy and communication performance.Comment: 7 pages, 8 figure

Physiological responses of Porphyra haitanesis to different copper and zinc concentrations

No presente estudo foram investigadas as respostas fisiológicas da alga vermelha Porphyra haitanesis às elevadas concentrações de cobre (acima de 50 μM) e de zinco (acima de 100 μM). Os resultados mostram que os efeitos de Cu2+ e Zn2+ sobre o crescimento, pigmentos fotossintéticos (clorofilas e carotenóides), ficobiliproteína e metabolismo (o espectro de emissão de fluorescência e as atividades do fotossistema) não seguem o mesmo padrão. A taxa de crescimento relativo foi inibida por diferentes concentrações de Cu2+ e, em presença de Zn2+, aumentou ligeiramente em baixas concentrações (abaixo de 10 μM) e foi inibida em altas concentrações. Por outro lado, os teores de ficoeritrina apresentaram leve aumento em concentrações relativamente baixas de Cu2+ e Zn2+ (até 1 μM Cu2+ e até 20 μM Zn2+, respectivamente) e foram inibidas por altas concentrações. Além disso, tanto a fotossíntese quanto a respiração mostraram aumento nas trocas de oxigênio em resposta às concentrações relativamente baixas de Cu2+ (até 1 μM) e de Zn2+ (até 10 μM), além da redução em concentrações relativamente altas desses metais. Adicionalmente, as atividades fotoredutoras e as emissões de fluorescência do fotossistema II (PSII) foram incrementadas em baixas concentrações de Cu2+ (até 0,1 μM) e de Zn2+ (até 10 μM) e inibidas por altas concentrações. Desta forma, a intensidade da fluorescência da clorofila-a e dos centros de reação ativa PSII seguiram um padrão semelhante em resposta às elevadas concentrações de Cu2+ e Zn2+. Esses resultados sugerem que baixas concentrações de Cu2+ e Zn2+ afetam o metabolismo de P. haitanesis, que se torna inibido por altas concentrações desses metais.In the present study, several physiological responses of the red marine alga Porphyra haitanesis to elevated concentrations of copper (up to 50 μM) and zinc (up to 100 μM) were investigated. Our results showed that the effects of Cu2+ and Zn2+ on growth, photosynthetic pigments (chlorophylls and carotenoids), phycobiliprotein and metabolism (the fluorescence emission spectra and the activities of photosystemII) did not follow the same pattern. The relative growth rate was inhibited by different concentrations of Cu2+, and was slightly increased at lower concentrations (up to 10 μM) and inhibited at higher Zn2+concentrations. On the other hand, the phycoerythrin contents were slightly increased at relatively low concentrations (up to 1 μM Cu2+ or 20 μM Zn2+) and inhibited by high Cu2+ and Zn2+ concentrations. Moreover, photosynthesis and respiration showed an increase in the amount of oxygen exchange in response to relatively low Cu2+ (up to 1 μM) and Zn2+ concentrations (up to 10 μM), and a reduction to relatively high Cu2+ and Zn2+ concentrations. Oxygen evolution was more sensitive than oxygen uptake to Cu2+ and Zn2+. In addition, the photoreductive activities and fluorescence emission of photosystem II (PS II) were enhanced by lower concentrations of Cu2+ (up to 0.1 μM) and Zn2+ (up to 10 μM) and inhibited by higher concentrations. Furthermore, the intensity of chlorophyll a fluorescence and the active PSII reaction centers followed a similar pattern in response to elevated concentrations of Cu2+ and Zn2+. These results suggest that lower concentrations of Cu2+ and Zn2+ affected the metabolism of P. haitanesis, which was inhibited by higher concentrations of these metals

Single-atom-layer traps in a solid electrolyte for lithium batteries

In order to fully understand the lithium-ion transport mechanism in solid electrolytes for batteries, not only the periodic lattice but also the non-periodic features that disrupt the ideal periodicity must be comprehensively studied. At present only a limited number of non-periodic features such as point defects and grain boundaries are considered in mechanistic studies. Here, we discover an additional type of non-periodic feature that significantly influences ionic transport; this feature is termed a “single-atom-layer trap” (SALT). In a prototype solid electrolyte Li0.33La0.56TiO3, the single-atom-layer defects that form closed loops, i.e., SALTs, are found ubiquitous by atomic-resolution electron microscopy. According to ab initio calculations, these defect loops prevent large volumes of materials from participating in ionic transport, and thus severely degrade the total conductivity. This discovery points out the urgency of thoroughly investigating different types of non-periodic features, and motivates similar studies for other solid electrolytes

Atomically Intimate Contact between Solid Electrolytes and Electrodes for Li Batteries

Solid electrolytes, as a promising replacement for the flammable liquid electrolyte in conventional Li-ion batteries, may greatly alleviate the safety issues and improve the energy density. However, mainstream electrodes are also solid. If solid electrolytes were employed, creating intimate electrode-electrolyte contact similar to that between solid and liquid would be quite difficult. Here we discovered that, by forming epitaxial interfaces, such a seamless solid-solid contact can happen between two widely studied systems: the Li-rich layered electrode and perovskite solid electrolyte. Atomic-resolution electron microscopy unambiguously demonstrated that the former can be epitaxially embedded into the latter. The solid-solid composite electrode formed this way exhibited a rate capability no lower than the one based on solid-liquid contact. With the periodic misfit dislocations reconciling structural differences, such epitaxy can tolerate large lattice mismatch, and thus may occur between many layered electrodes and perovskite solid electrolytes

A fluidic platform for mobility evaluation of zebrafish with gene deficiency

IntroductionZebrafish is a suitable animal model for molecular genetic tests and drug discovery due to its characteristics including optical transparency, genetic manipulability, genetic similarity to humans, and cost-effectiveness. Mobility of the zebrafish reflects pathological conditions leading to brain disorders, disrupted motor functions, and sensitivity to environmental challenges. However, it remains technologically challenging to quantitively assess zebrafish's mobility in a flowing environment and simultaneously monitor cellular behavior in vivo.MethodsWe herein developed a facile fluidic device using mechanical vibration to controllably generate various flow patterns in a droplet housing single zebrafish, which mimics its dynamically flowing habitats.ResultsWe observe that in the four recirculating flow patterns, there are two equilibrium stagnation positions for zebrafish constrained in the droplet, i.e., the “source” with the outward flow and the “sink” with the inward flow. Wild-type zebrafish, whose mobility remains intact, tend to swim against the flow and fight to stay at the source point. A slight deviation from streamline leads to an increased torque pushing the zebrafish further away, whereas zebrafish with motor neuron dysfunction caused by lipin-1 deficiency are forced to stay in the “sink,” where both their head and tail align with the flow direction. Deviation angle from the source point can, therefore, be used to quantify the mobility of zebrafish under flowing environmental conditions. Moreover, in a droplet of comparable size, single zebrafish can be effectively restrained for high-resolution imaging.ConclusionUsing the proposed methodology, zebrafish mobility reflecting pathological symptoms can be quantitively investigated and directly linked to cellular behavior in vivo

Crystal structure of the DNA binding domain of the transcription factor T-bet suggests simultaneous recognition of distant genome sites

The transcription factor T-bet (Tbox protein expressed in T cells) is one of the master regulators of both the innate and adaptive immune responses. It plays a central role in T-cell lineage commitment, where it controls the T[subscript H]1 response, and in gene regulation in plasma B-cells and dendritic cells. T-bet is a member of the Tbox family of transcription factors; however, T-bet coordinately regulates the expression of many more genes than other Tbox proteins. A central unresolved question is how T-bet is able to simultaneously recognize distant Tbox binding sites, which may be located thousands of base pairs away. We have determined the crystal structure of the Tbox DNA binding domain (DBD) of T-bet in complex with a palindromic DNA. The structure shows a quaternary structure in which the T-bet dimer has its DNA binding regions splayed far apart, making it impossible for a single dimer to bind both sites of the DNA palindrome. In contrast to most other Tbox proteins, a single T-bet DBD dimer binds simultaneously to identical half-sites on two independent DNA. A fluorescence-based assay confirms that T-bet dimers are able to bring two independent DNA molecules into close juxtaposition. Furthermore, chromosome conformation capture assays confirm that T-bet functions in the direct formation of chromatin loops in vitro and in vivo. The data are consistent with a looping/synapsing model for transcriptional regulation by T-bet in which a single dimer of the transcription factor can recognize and coalesce distinct genetic elements, either a promoter plus a distant regulatory element, or promoters on two different genes.United States. National Institutes of Health (P01-AI056296

MicroRec: Efficient Recommendation Inference by Hardware and Data Structure Solutions

Deep neural networks are widely used in personalized recommendation systems. Unlike regular DNN inference workloads, recommendation inference is memory-bound due to the many random memory accesses needed to lookup the embedding tables. The inference is also heavily constrained in terms of latency because producing a recommendation for a user must be done in about tens of milliseconds. In this paper, we propose MicroRec, a high-performance inference engine for recommendation systems. MicroRec accelerates recommendation inference by (1) redesigning the data structures involved in the embeddings to reduce the number of lookups needed and (2) taking advantage of the availability of High-Bandwidth Memory (HBM) in FPGA accelerators to tackle the latency by enabling parallel lookups. We have implemented the resulting design on an FPGA board including the embedding lookup step as well as the complete inference process. Compared to the optimized CPU baseline (16 vCPU, AVX2-enabled), MicroRec achieves 13.8~14.7x speedup on embedding lookup alone and 2.5$~5.4x speedup for the entire recommendation inference in terms of throughput. As for latency, CPU-based engines needs milliseconds for inferring a recommendation while MicroRec only takes microseconds, a significant advantage in real-time recommendation systems.Comment: Accepted by MLSys'21 (the 4th Conference on Machine Learning and Systems