1,026 research outputs found
Age structure landscapes emerge from the equilibrium between aging and rejuvenation in bacterial populations.
The physiological asymmetry between daughters of a mother bacterium is produced by the inheritance of either old poles, carrying non-genetic damage, or newly synthesized poles. However, as bacteria display long-term growth stability leading to physiological immortality, there is controversy on whether asymmetry corresponds to aging. Here we show that deterministic age structure landscapes emerge from physiologically immortal bacterial lineages. Through single-cell microscopy and microfluidic techniques, we demonstrate that aging and rejuvenating bacterial lineages reach two distinct states of growth equilibria. These equilibria display stabilizing properties, which we quantified according to the compensatory trajectories of continuous lineages throughout generations. Finally, we show that the physiological asymmetry between aging and rejuvenating lineages produces complex age structure landscapes, resulting in a deterministic phenotypic heterogeneity that is neither an artifact of starvation nor a product of extrinsic damage. These findings indicate that physiological immortality and cellular aging can both be manifested in single celled organisms
TISE: Bag of Metrics for Text-to-Image Synthesis Evaluation
In this paper, we conduct a study on the state-of-the-art methods for
text-to-image synthesis and propose a framework to evaluate these methods. We
consider syntheses where an image contains a single or multiple objects. Our
study outlines several issues in the current evaluation pipeline: (i) for image
quality assessment, a commonly used metric, e.g., Inception Score (IS), is
often either miscalibrated for the single-object case or misused for the
multi-object case; (ii) for text relevance and object accuracy assessment,
there is an overfitting phenomenon in the existing R-precision (RP) and
Semantic Object Accuracy (SOA) metrics, respectively; (iii) for multi-object
case, many vital factors for evaluation, e.g., object fidelity, positional
alignment, counting alignment, are largely dismissed; (iv) the ranking of the
methods based on current metrics is highly inconsistent with real images. To
overcome these issues, we propose a combined set of existing and new metrics to
systematically evaluate the methods. For existing metrics, we offer an improved
version of IS named IS* by using temperature scaling to calibrate the
confidence of the classifier used by IS; we also propose a solution to mitigate
the overfitting issues of RP and SOA. For new metrics, we develop counting
alignment, positional alignment, object-centric IS, and object-centric FID
metrics for evaluating the multi-object case. We show that benchmarking with
our bag of metrics results in a highly consistent ranking among existing
methods that is well-aligned with human evaluation. As a by-product, we create
AttnGAN++, a simple but strong baseline for the benchmark by stabilizing the
training of AttnGAN using spectral normalization. We also release our toolbox,
so-called TISE, for advocating fair and consistent evaluation of text-to-image
models.Comment: Accepted to ECCV 2022; TISE toolbox is available at
https://github.com/VinAIResearch/tise-toolbo
Mapping localized surface plasmons within silver nanocubes using cathodoluminescence hyperspectral imaging
Localized surface plasmons within silver nanocubes less than 50 nm in size are investigated using high resolution cathodoluminescence hyperspectral imaging. Multivariate statistical analysis of the multidimensional luminescence dataset allows both the identification of distinct spectral features in the emission and the mapping of their spatial distribution. These results show a 490 nm peak emitted from the cube faces, with shorter wavelength luminescence coming from the vertices and edges; this provides direct experimental confirmation of theoretical predictions
Vascular responses of the extremities to transdermal application of vasoactive agents in Caucasian and African descent individuals
This is an accepted manuscript of an article published by Springer in European Journal of Applied Physiology on 04/04/2015, available online: https://doi.org/10.1007/s00421-015-3164-2
The accepted version of the publication may differ from the final published version.© 2015, Springer-Verlag Berlin Heidelberg. Purpose: Individuals of African descent (AFD) are more susceptible to non-freezing cold injury than Caucasians (CAU) which may be due, in part, to differences in the control of skin blood flow. We investigated the skin blood flow responses to transdermal application of vasoactive agents. Methods: Twenty-four young males (12 CAU and 12 AFD) undertook three tests in which iontophoresis was used to apply acetylcholine (ACh 1 w/v %), sodium nitroprusside (SNP 0.01 w/v %) and noradrenaline (NA 0.5 mM) to the skin. The skin sites tested were: volar forearm, non-glabrous finger and toe, and glabrous finger (pad) and toe (pad). Results: In response to SNP on the forearm, AFD had less vasodilatation for a given current application than CAU (P = 0.027–0.004). ACh evoked less vasodilatation in AFD for a given application current in the non-glabrous finger and toe compared with CAU (P = 0.043–0.014) with a lower maximum vasodilatation in the non-glabrous finger (median [interquartile], AFD n = 11, 41[234] %, CAU n = 12, 351[451] %, P = 0.011) and non-glabrous toe (median [interquartile], AFD n = 9, 116[318] %, CAU n = 12, 484[720] %, P = 0.018). ACh and SNP did not elicit vasodilatation in the glabrous skin sites of either group. There were no ethnic differences in response to NA. Conclusion: AFD have an attenuated endothelium-dependent vasodilatation in non-glabrous sites of the fingers and toes compared with CAU. This may contribute to lower skin temperature following cold exposure and the increased risk of cold injuries experienced by AFD.Published versio
Effect of high temperature and water stress on pollen germination and spikelet fertility in rice
In future climates, rice could more frequently be subjected to simultaneous high temperature and water stress during sensitive developmental stages such as flowering. In this study, five rice genotypes were exposed to high temperature, water stress and combined high temperature and water stress during flowering to quantify their response through spikelet fertility. Microscopic analyses revealed significant differences in anther dehiscence between treatments and genotypes, with a moderately high association with the number of germinated pollen grains on the stigma. There was a strong relationship between spikelet fertility and the number of germinated pollen on stigmas. Although, all three stress treatments resulted in spikelet sterility, high-temperature stress caused the highest sterility in all five genotypes. A cumulative linear decline in spikelet fertility with increasing duration of independent high-temperature stress and in combination with water stress was quantified. Better anther dehiscence, higher in vivo pollen germination, and higher spikelet fertility were observed in both the N22 accessions compared with IR64, Apo and Moroberekan under high temperature, water stress and combined stress, indicating its ability to tolerate multiple abiotic stresses
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