Search for: All records

Calcium waves and oscillation during embryonic development are key elements in the intricate process of molluscan shell formation. However, understanding calcium dynamics in the early embryonic shell formation in gastropod development is still insufficient. The present study explores the role of calcium flux in early shell formation within the embryo of gastropod Biomphalaria glabrata. We hypothesized that the role of calcium is not only in providing a critical element for shell formation but also in serving as a signaling molecule for the genetic regulation of calcification. The calcium flux was visualized using the Fura-2 and Fluo-4 calcium indicators through the trochophore (72 hours) and veliger (120 hours) stages of B. glabrata development. The dynamics of calcium signals were correlated to the rapid transition from motile trochophore to veliger, marked by cilia-mediated movement and premature shell and foot development. According to our observation, the intracellular calcium signals were attenuated from 72 to 120 hours of embryo development. The expression profiles of genes encoding calmodulin and related protein kinase following the calcium flux in embryos suggested a critical role of the calcium-binding proteins in the early shell development of gastropods. Although the embryonic calcium dynamics and the related signaling pathway of shell formation are under further observation and analysis, the role of calcium in the singling pathway of shell formation has been demonstrated by this preliminary study. 

Millions of tons of plastics enter the oceans yearly, and they can be fragmented by ultraviolet and mechanical means into nanoplastics. Here, we report the direct observation of nanoplastics in global ocean water leveraging a unique shrinking surface bubble deposition (SSBD) technique. SSBD involves optically heating plasmonic nanoparticles to form a surface bubble and leveraging the Marangoni flow to concentrate suspended nanoplastics onto the surface, allowing direct visualization using electron microscopy. With the plasmonic nanoparticles co-deposited in SSBD, the surface-enhanced Raman spectroscopy effect is enabled for direct chemical identification of trace amounts of nanoplastics. In the water samples from two oceans, we observed nanoplastics made of nylon, polystyrene, and polyethylene terephthalate—all common in daily consumables. The plastic particles have diverse morphologies, such as nanofibers, nanoflakes, and ball-stick nanostructures. These nanoplastics may profoundly affect marine organisms, and our results can provide critical information for appropriately designing their toxicity studies.

 

Automated text simplification aims to produce simple versions of complex texts. This task is especially useful in the medical domain, where the latest medical findings are typically communicated via complex and technical articles. This creates barriers for laypeople seeking access to up-to-date medical findings, consequently impeding progress on health literacy. Most existing work on medical text simplification has focused on monolingual settings, with the result that such evidence would be available only in just one language (most often, English). This work addresses this limitation via multilingual simplification, i.e., directly simplifying complex texts into simplified texts in multiple languages. We introduce MultiCochrane, the first sentence-aligned multilingual text simplification dataset for the medical domain in four languages: English, Spanish, French, and Farsi. We evaluate fine-tuned and zero-shot models across these languages with extensive human assessments and analyses. Although models can generate viable simplified texts, we identify several outstanding challenges that this dataset might be used to address. 

In this paper, we consider the physical layer security of an RIS-assisted multiple-antenna communication system with randomly located eavesdroppers. The exact distributions of the received signal-to-noise-ratios (SNRs) at the legitimate user and the eavesdroppers located according to a Poisson point process (PPP) are derived, and a closed-form expression for the secrecy outage probability (SOP) is obtained. It is revealed that the secrecy performance is mainly affected by the number of RIS reflecting elements, and the impact of the transmit antennas and transmit power at the base station is marginal. In addition, when the locations of the randomly located eavesdroppers are unknown, deploying the RIS closer to the legitimate user rather than to the base station is shown to be more efficient. We also perform an analytical study demonstrating that the secrecy diversity order depends on the path loss exponent of the RIS-to-ground links. Finally, numerical simulations are conducted to verify the accuracy of these theoretical observations.