47 research outputs found
Shape asymmetries and lopsidedness-radial-alignment in simulated galaxies
Galaxies are observed to be lopsided, meaning that they are more massive and
more extended along one direction than the opposite. However, the galaxies
generated in cosmological simulations are much less lopsided, inconsistent with
observations. In this work, we provide a statistical analysis of the lopsided
morphology of 2148 simulated isolated satellite galaxies generated by TNG50-1
simulation, incorporating the effect of tidal fields from halo centres. We
study the radial alignment (RA) between the major axes of satellites and the
radial direction of their halo centres within truncation radii of ,
and . According to our results, RA is absent for all these
truncations. We also calculate the far-to-near-side semi-axial ratios of the
major axes, denoted by , which measures the semi-axial ratios of the
major axes in the hemispheres between backwards (far-side) and facing
(near-side) the halo centres. If the satellites are truncated within radii of
and with being the stellar half mass radius, the numbers of
satellites with longer semi-axes on the far-side are found to be almost equal
to those with longer semi-axes on the near-side. Within a larger truncated
radius of , the number of satellites with axial ratios is
about more than that with . Therefore, the tidal fields
from halo centres play a minor role in the generation of lopsided satellites.
The lopsidedness radial alignment (LRA), i.e., an alignment of long
semi-major-axes along the radial direction of halo centres, is further studied.
No clear evidence of LRA is found in our sample within the framework of
CDM Newtonian dynamics. In comparison, the LRA can be naturally
induced by the external fields from the central host galaxy in Milgromian
dynamics. (See paper for full abstract)Comment: 16 pages, 12 figures, 3 tables, submitted to MNRA
Regulation of nitric oxide signaling by formation of a distal receptor-ligand complex.
The binding of nitric oxide (NO) to the heme cofactor of heme-nitric oxide/oxygen binding (H-NOX) proteins can lead to the dissociation of the heme-ligating histidine residue and yield a five-coordinate nitrosyl complex, an important step for NO-dependent signaling. In the five-coordinate nitrosyl complex, NO can reside on either the distal or proximal side of the heme, which could have a profound influence over the lifetime of the in vivo signal. To investigate this central molecular question, we characterized the Shewanella oneidensis H-NOX (So H-NOX)-NO complex biophysically under limiting and excess NO conditions. The results show that So H-NOX preferably forms a distal NO species with both limiting and excess NO. Therefore, signal strength and complex lifetime in vivo will be dictated by the dissociation rate of NO from the distal complex and the rebinding of the histidine ligand to the heme
Understanding activity trends in electrochemical water oxidation to form hydrogen peroxide
Electrochemical production of hydrogen peroxide (H2O2) from water oxidation could provide a very attractive route to locally produce a chemically valuable product from an abundant resource. Herein using density functional theory calculations, we predict trends in activity for water oxidation towards H2O2 evolution on four different metal oxides, i.e., WO3, SnO2, TiO2 and BiVO4. The density functional theory predicted trend for H2O2 evolution is further confirmed by our experimental measurements. Moreover, we identify that BiVO4 has the best H2O2 generation amount of those oxides and can achieve a Faraday efficiency of about 98% for H2O2 production
Effective Lymph Nodes Detection in CT Scans Using Location Debiased Query Selection and Contrastive Query Representation in Transformer
Lymph node (LN) assessment is a critical, indispensable yet very challenging
task in the routine clinical workflow of radiology and oncology. Accurate LN
analysis is essential for cancer diagnosis, staging, and treatment planning.
Finding scatteredly distributed, low-contrast clinically relevant LNs in 3D CT
is difficult even for experienced physicians under high inter-observer
variations. Previous automatic LN detection works typically yield limited
recall and high false positives (FPs) due to adjacent anatomies with similar
image intensities, shapes, or textures (vessels, muscles, esophagus, etc). In
this work, we propose a new LN DEtection TRansformer, named LN-DETR, to achieve
more accurate performance. By enhancing the 2D backbone with a multi-scale 2.5D
feature fusion to incorporate 3D context explicitly, more importantly, we make
two main contributions to improve the representation quality of LN queries. 1)
Considering that LN boundaries are often unclear, an IoU prediction head and a
location debiased query selection are proposed to select LN queries of higher
localization accuracy as the decoder query's initialization. 2) To reduce FPs,
query contrastive learning is employed to explicitly reinforce LN queries
towards their best-matched ground-truth queries over unmatched query
predictions. Trained and tested on 3D CT scans of 1067 patients (with 10,000+
labeled LNs) via combining seven LN datasets from different body parts (neck,
chest, and abdomen) and pathologies/cancers, our method significantly improves
the performance of previous leading methods by > 4-5% average recall at the
same FP rates in both internal and external testing. We further evaluate on the
universal lesion detection task using NIH DeepLesion benchmark, and our method
achieves the top performance of 88.46% averaged recall across 0.5 to 4 FPs per
image, compared with other leading reported results.Comment: Technical repor
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
Decoupled Object-Independent Image Features for Fine Phasing of Segmented Mirrors Using Deep Learning
A segmented primary mirror is very important for extra-large astronomical telescopes, in order to detect the phase error between segmented mirrors. Traditional iterative algorithms are hard to detect co−phasing aberrations in real time due to the long-time iterative process. Deep learning has shown large potential in wavefront sensing, and it gradually focuses on detecting piston error. However, the current methods based on deep learning are mainly applied to coarse phase sensing, and only consider the detection of piston error with no tip/tilt errors, which is inconsistent with reality. In this paper, by innovatively designing the form of pupil mask, and further updating the OTF in the frequency domain, we obtain a new decoupled independent feature image that can simultaneously detect the piston error and tilt/tilt error of all sub-mirrors, which is effectively decoupled, and eliminates the dependence of the data set on the imaging object. Then, the Bi−GRU network is used to recover phase error information with high accuracy from the feature image proposed in this paper. The network’s detection accuracy ability is verified under single wavelength and broadband spectrum in simulation. This paper demonstrates that co−phasing errors can be accurately decoupled and extracted by the new feature image we proposed and will contribute to the fine phasing accuracy and practicability of the extended scenes for the segmented telescopes