56 research outputs found
The Photosynthetic Characteristics of Wild <em>Cymbidium faberi</em> in the Qinling Mountains of Central China
The large flowers of orchids make them popular as cultivated plants. Seven species of orchids in the genus Cymbidium (Orchidaceae) have been crossbred to create more than 220 hybrids that serve as popular cultivated ornamentals. The present study examined the daily variation in the patterns of the net photosynthetic rate and the photosynthetic response of wild Cymbidium faberi in the Qinling Mountains in northwestern China. The photosynthetic characteristics of this species were studied under natural conditions with a portable photosynthesis system. Double peaks were observed in the net photosynthetic rate with one around 09:00 and another around 17:00 in spring, as well as one around 11:00 and another around 15:00 in winter. Midday depression of photosynthesis was observed in wild C. faberi plants around 13:00 in both spring and winter. The net photosynthetic rate was strongly positively correlated with both stomatal conductance (R = 0.913) and the transpiration rate (R = 0.659) and weakly negatively correlated with the intercellular carbon dioxide concentration (R = −0.094). The results show that the light compensation point (LCP) and the light saturation point (LSP) of wild C. faberi were 25.78 and 384 μmol m−2 s−1, respectively. The result provides reference for cultivation management especially in light management of Cymbidium
Digital twin brain: a bridge between biological intelligence and artificial intelligence
In recent years, advances in neuroscience and artificial intelligence have
paved the way for unprecedented opportunities for understanding the complexity
of the brain and its emulation by computational systems. Cutting-edge
advancements in neuroscience research have revealed the intricate relationship
between brain structure and function, while the success of artificial neural
networks highlights the importance of network architecture. Now is the time to
bring them together to better unravel how intelligence emerges from the brain's
multiscale repositories. In this review, we propose the Digital Twin Brain
(DTB) as a transformative platform that bridges the gap between biological and
artificial intelligence. It consists of three core elements: the brain
structure that is fundamental to the twinning process, bottom-layer models to
generate brain functions, and its wide spectrum of applications. Crucially,
brain atlases provide a vital constraint, preserving the brain's network
organization within the DTB. Furthermore, we highlight open questions that
invite joint efforts from interdisciplinary fields and emphasize the
far-reaching implications of the DTB. The DTB can offer unprecedented insights
into the emergence of intelligence and neurological disorders, which holds
tremendous promise for advancing our understanding of both biological and
artificial intelligence, and ultimately propelling the development of
artificial general intelligence and facilitating precision mental healthcare
Mitophagy links oxidative stress conditions and neurodegenerative diseases
Mitophagy is activated by a number of stimuli, including hypoxia, energy stress, and increased oxidative phosphorylation activity. Mitophagy is associated with oxidative stress conditions and central neurodegenerative diseases. Proper regulation of mitophagy is crucial for maintaining homeostasis; conversely, inadequate removal of mitochondria through mitophagy leads to the generation of oxidative species, including reactive oxygen species and reactive nitrogen species, resulting in various neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, and amyotrophic lateral sclerosis. These diseases are most prevalent in older adults whose bodies fail to maintain proper mitophagic functions to combat oxidative species. As mitophagy is essential for normal body function, by targeting mitophagic pathways we can improve these disease conditions. The search for effective remedies to treat these disease conditions is an ongoing process, which is why more studies are needed. Additionally, more relevant studies could help establish therapeutic conditions, which are currently in high demand. In this review, we discuss how mitophagy plays a significant role in homeostasis and how its dysregulation causes neurodegeneration. We also discuss how combating oxidative species and targeting mitophagy can help treat these neurodegenerative diseases
Structure-Independent Conductance of Thiophene-Based Single-Stacking Junctions.
Intermolecular charge transport is crucial in π-conjugated materials but the experimental investigation remained challenging. Here, we show that charge transport through intermolecular and intramolecular paths in single-molecule and single-stacking thiophene junctions could be investigated using the mechanically controllable break junction (MCBJ) technique. We found that intermolecular charge transport ability through different single-stacking junctions is approximately independent of molecular structures, which contrasts with the strong length dependence of conductance in single-molecule junctions with the same building blocks, and the dominant charge transport path of molecules with two anchors transits from intramolecular to intermolecular paths when the conjugation pattern increased. The increase of conjugation further leads to higher binding probabilities due to the variation in binding energies supported by density functional theory (DFT) calculations. Our results demonstrate that intermolecular charge transport is not only the limiting step but also provides the efficient and dominate charge transport path at the single-molecule scale
A Search for Technosignatures Around 11,680 Stars with the Green Bank Telescope at 1.15-1.73 GHz
We conducted a search for narrowband radio signals over four observing
sessions in 2020-2023 with the L-band receiver (1.15-1.73 GHz) of the 100 m
diameter Green Bank Telescope. We pointed the telescope in the directions of 62
TESS Objects of Interest, capturing radio emissions from a total of ~11,680
stars and planetary systems in the ~9 arcminute beam of the telescope. All
detections were either automatically rejected or visually inspected and
confirmed to be of anthropogenic nature. In this work, we also quantified the
end-to-end efficiency of radio SETI pipelines with a signal injection and
recovery analysis. The UCLA SETI pipeline recovers 94.0% of the injected
signals over the usable frequency range of the receiver and 98.7% of the
injections when regions of dense RFI are excluded. In another pipeline that
uses incoherent sums of 51 consecutive spectra, the recovery rate is ~15 times
smaller at ~6%. The pipeline efficiency affects calculations of transmitter
prevalence and SETI search volume. Accordingly, we developed an improved Drake
Figure of Merit and a formalism to place upper limits on transmitter prevalence
that take the pipeline efficiency and transmitter duty cycle into account.
Based on our observations, we can state at the 95% confidence level that fewer
than 6.6% of stars within 100 pc host a transmitter that is detectable in our
search (EIRP > 1e13 W). For stars within 20,000 ly, the fraction of stars with
detectable transmitters (EIRP > 5e16 W) is at most 3e-4. Finally, we showed
that the UCLA SETI pipeline natively detects the signals detected with AI
techniques by Ma et al. (2023).Comment: 22 pages, 9 figures, submitted to AJ, revise
Robust estimation of bacterial cell count from optical density
Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data
Ultrasound microbubble contrast agent – carried chemotherapeutic drug microbubbles
With the continuous research and development of ultrasound microbubble contrast agent-carried chemotherapeutic drug microbubbles, ultrasound microbubble contrast agent not only facilitates the early detection and early diagnosis of tumors but also provides a new direction and development prospect for the drug delivery route. With a broad development prospect, it is expected to become a new safe, effective and non-invasive treatment. This paper reviews the biological effects and research progress of contrast-enhanced microbubble-loaded chemotherapy drugs in tumor therapy
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